Iran said Sunday it would no longer abide by any of the limits of its unravelling 2015 nuclear deal with world powers after a US airstrike killed a top Iranian general in Baghdad, ending an accord that blocked Tehran from having enough material to build an atomic weapon.

The announcement came Sunday night after another Iranian official said it would consider taking even-harsher steps over the US killing of Gen. Qasem Soleimani on Friday.

Hundreds of thousands of people flooded the streets on Sunday in Iran to walk alongside a casket carrying the remains of Soleimani, the former leader of its expeditionary Quds Force that organises Tehran's proxy forces in the wider Mideast.

The leader of one such proxy, Lebanon's Hezbollah, said Soleimani's killing made US military bases, warships and service members spread across the region fair targets for attacks. A former Revolutionary Guard leader suggested the Israeli city of Haifa and “centres” like Tel Aviv could be targeted.

Iran's state TV cited a statement by President Hassan Rouhani's administration saying the country will not observe limitations on its enrichment, the amount of stockpiled enriched uranium as well as research and development in its nuclear activities.

It did not elaborate on what levels it would immediately reach in its programme.

The International Atomic Energy Agency, the United Nations watchdog observing Iran's programme, did not immediately respond to a request for comment. However, Iran said that its cooperation with the IAEA will continue as before.

Meanwhile, Iraq's parliament voted in favour of a resolution calling for an end of the foreign military presence in their nation, an effort aimed at expelling the 5,000 US troops stationed there over the war against the Islamic State group.

Soleimani's killing has escalated the crisis between Tehran and Washington after months of trading attacks and threats that have put the wider Middle East on edge. The conflict is rooted in President Donald Trump pulling out of Iran's atomic accord and imposing sanctions that have crippled Iran's economy.

Iran has promised harsh revenge” for the US attack, which shocked Iranians across all political lines. Many saw Soleimani as a pillar of the Islamic Republic at a moment when it is beset by US sanctions and recent anti-government protests.

Retaliation for Soleimani could potentially come through the proxy forces which he oversaw. Soleimani's longtime deputy Esmail Ghaani already has taken over as the Quds Force's commander.

The US Embassy in Saudi Arabia separately warned Americans of the heightened risk of missile and drone attacks.

Late Saturday, a series of rockets launched in Baghdad fell inside or near the Green Zone, which houses government offices and foreign embassies, including the US Embassy.

Trump wrote on Twitter afterward that the US had already targeted 52 Iranian sites (representing the 52 American hostages taken by Iran many years ago), some at a very high level & important to Iran & the Iranian culture.

Trump did not identify the targets but added that they would be "HIT VERY FAST AND VERY HARD".

The 1954 Hague Convention, of which the US is a party, bars any military from direct hostilities against cultural property.” However, such sites can be targeted if they have been re-purposed and turned into a legitimate military objective,” according to the International Committee of the Red Cross.

Iran, home to 24 UNESCO World Heritage sites, has in the past reportedly guarded the sprawling tomb complex of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini, with surface-to-air missiles.

After thousands in Baghdad on Saturday mourned Soleimani and others killed in the strike, authorities flew the general's body to the southwestern Iranian city of Ahvaz. An honour guard stood by early Sunday as mourners carried the flag-draped coffins of Soleimani and other Guard members off the tarmac.

The caskets then moved slowly through streets choked with mourners wearing black, beating their chests and carrying posters with Soleimani's portrait. Demonstrators also carried red Shia flags, which traditionally both symbolise the spilled blood of someone unjustly killed and call for their deaths to be avenged.

Officials brought Soleimani's body to Ahvaz, a city that was a focus of fighting during the bloody, 1980-88 war between Iraq and Iran in which the general slowly grew to prominence. After that war, Soleimani joined the Guard's newly formed Quds, or Jersualem, Force, an expeditionary force that works with Iranian proxy forces in countries like Iraq, Lebanon and Yemen.

Authorities then took Soleimani's body to the city of Mashhad later Sunday. State TV estimated that a million mourners came out to the Imam Reza shrine to pay their respects, although that number could not be independently verified. Soleimani's remains will go to Tehran and Qom on Monday for public mourning processions, followed by his hometown of Kerman for burial on Tuesday.

This marks the first time Iran honored a single man with a multi-city ceremony. Not even Khomeini received such a processional with his death in 1989. Soleimani on Monday will lie in state at Tehran's famed Musalla mosque as the revolutionary leader did before him.

Soleimani was the architect of Iran's regional policy of mobilizing militias across Iraq, Syria and Lebanon, including in the war against the militant Islamic State group. He was also blamed for attacks on US troops and American allies going back decades.

Although it's unclear how or when Iran may respond, any retaliation was likely to come after three days of mourning declared in both Iran and Iraq.

Mohsen Rezaei, a former leader of the Guard, told a crowd of mourners in Tehran that the Israeli city of Haifa and other centers like Tel Aviv could be targeted. Rezaei earlier alleged without offering evidence that Israel leaked information to the US about Soleimani's whereabouts, which allowed them to carry out the drone strike.

"Rest assured we will level to the ground Haifa and Israeli centers so that Israel will be wiped out," he said. "The issue is very serious for the Iranian nation. You hit us and you should get hit. You attacked us and it is the Iranian nation's right."

Iranian officials planned to meet on Sunday night to discuss taking a fifth step away from its 2015 nuclear deal with world powers, one that could be even greater than planned, Foreign Ministry spokesman Abbas Mousavi told journalists.

"In the world of politics, all developments are interconnected,” Mousavi said.

Iran previously has broken limits of its enrichment, its stockpiles and its centrifuges, as well as restarted enrichment at an underground facility.

The Iranian parliament on Sunday opened with lawmakers in unison chanting: Death to America! Parliament speaker Ali Larijani compared Soleimani's killing to the 1953 CIA-backed coup that cemented the Shah's power and to the US Navy's shootdown of an Iranian passenger plane in 1988 that killed 290 people. He also described American officials as following the law of the jungle.

Rain fell at the shrine in Mashhad late Sunday as an imam delivered a sermon over the coffins of Soleimani and others stood. The crowd surged and shouted as he preached. Mourners threw clothing up to officials accompanying the remains to have the fabric be brushed against the caskets in a belief it would carry God's blessings to them.