RIYADH/TEHRAN/DUBAI: Saudi Arabia on Thursday proposed a five-day humanitarian ceasefire in Yemen to allow aid deliveries, calling on Houthi rebels to accept the offer.

Foreign Minister Adel al-Jubeir announced the proposal after talks with visiting United States Secretary of State John Kerry, who urged the rebels to agree to the initiative.

Kerry was in Saudi Arabia to push for a “pause” in air strikes in Yemen while the country's exiled authorities urged a foreign ground offensive against rebels.

Weeks of air strikes by a Saudi-led coalition have failed to halt an advance by Houthi rebels in Yemen, and concern has been mounting over increasing civilian deaths and a growing humanitarian crisis.

In a letter to the Security Council on Wednesday, Yemen's mission to the United Nations said the rebels were carrying out “barbaric violations” in the southern city of Aden and pleaded for action.

“We urge the international community to quickly intervene by land forces to save Yemen, especially Aden and Taez,” the letter said.

After arriving in Riyadh on Wednesday, Kerry met Crown Prince Mohammed bin Nayef. On Thursday, he held talks with Hadi, now based in the Saudi capital, and with his Saudi counterpart Adel al-Jubeir.

Kerry was to cap his visit by meeting King Salman, after Riyadh said it is considering temporary halts in air raids to allow aid deliveries into Yemen.

Read more: UN’s Yemen envoy to visit Saudi Arabia

Yemen rebels committed 'possible war crimes': HRW

Human Rights Watch on Thursday accused Yemeni rebels of committing “possible war crimes” and urged all parties in the conflict to protect civilians.

The New York-based watchdog said rebel forces shot and killed two women in the main southern city of Aden last month and also unlawfully detained 10 local aid workers for up to two weeks.

“The incidents, possible war crimes, exemplify the grave threats to civilians in the embattled southern seaport,” said HRW.

HRW Deputy Director Middle East and North Africa Joe Stork warned that “the difficulty of investigating the fighting in Yemen may mean abuses like these in Aden are just the tip of the iceberg”.

He urged all fighters on the ground as well as the Saudi-led coalition carrying out air strikes against rebel positions across Yemen “to take steps to abide by the laws of war”.

At least 38 civilians were killed Wednesday and 95 were wounded, including women and children, when shelling hit people trying to escape Aden by sea, according to a new toll given by city health chief Al-Khader Laswar.

Health officials and a spokesman for militia forces loyal to exiled President Hadi blamed the rebels for the shelling.

Pro-Hadi forces, including military units and militia fighters, have been battling Houthi rebels and their allies for weeks in Aden.

Hadi's supporters have been backed by air strikes from a Saudi-led coalition that has imposed an air and naval blockade on the country.

“Aden's civilians are already in dire straits, without being attacked, detained, and held hostage,” Stork said.

“Leaders of the Houthis and other forces need to protect civilians, not abuse and terrorise them."

The rebels have been battling to take control of Aden's Tawahi neighbourhood, which houses the headquarters of the pro-Hadi Aden TV.

Laswar said five more civilians were killed overnight in “random rebel shelling on their homes in Tawahi”.

A military source meanwhile said that five Houthi rebels were killed in an ambush in Aden on Thursday.

Read more: Yemen rebels shell Saudi town, coalition warns of retaliation

Iran to send aid ship to Yemen

Iran's Red Crescent will send a ship carrying 2,500 tonnes of humanitarian aid to Yemen, official media said Thursday, following weeks of deadly fighting between Tehran-backed rebels and loyalist forces.

Officials at the Iranian Red Crescent have informed their Saudi counterparts by fax of the planned shipment, the IRNA news agency said, quoting the organisation's secretary general Ali Asghar Ahmadi.

The Iranian vessel is expected to leave on Saturday and will take about 10 days to reach Yemen, Ahmadi said.

Members of the Iranian Red Crescent will also be sent “to help the Yemeni people,” he added.

The Saudi-led coalition bombed the runway at the airport in the rebel-held capital Sanaa on April 28, saying an Iranian plane had “defied” a blockade on Yemeni airspace.

Days earlier, Iran summoned the Saudi envoy to protest after his country's warplanes allegedly turned back Iranian Red Crescent aid flights headed for Yemen.

Read more: Iran sees Yemen ceasefire in coming hours