An assailant opened fire on a police car Saturday in Istanbul, just hours after two other attacks against the police and Turkey's ruling party offices, media reports said.

The series of assaults, which authorities suggested were the work of ultra-leftists, come as the nation is reeling from an unprecedented series of attacks and bombings.

The shooter opened fire on officers in a car in the Esenyurt district of Istanbul, the Dogan news agency said. The assailant left a hand grenade before running away when officers shot back. No injuries were reported.

The attack came in the same area where the gunman blamed for the New Year shooting on an elite nightclub in Istanbul was arrested.

Saturday's gunfire came less than 12 hours after two rocket attacks in the city on a police headquarters and the ruling Justice and Development (AKP) Party's Istanbul offices late Friday.

No one was killed or injured in any of the three attacks, local media said.

Images in Turkish media showed an un-exploded rocket which had become stuck in a framed text of the Turkish national anthem inside the AKP offices.

No group claimed responsibility for the attacks but authorities suggested the outlawed ultra-leftist Revolutionary People's Liberation Party-Front (DHKP-C) could be to blame.

Turkey's Prime Minister Binali Yildirim said there was speculation that a “leftist terror group” was the culprit but said it was not clear which one, referring to the DHKP-C and another.

In recent years, there have been sporadic attacks by radicals from the DHKP-C, which seeks a Marxist revolution in Turkey and espouses a fiercely anti-Western agenda.

The attacks happened as the Turkish parliament in Ankara was voting on a draft bill to expand President Recep Tayyip Erdogan's powers, which was approved in the early hours of Saturday.

EU Affairs Minister Omer Celik said on Twitter such attacks target people and security services, but they also target “politics and (try) to influence decision making mechanisms”.

After multiple bombings in 2016 blamed on militants, the new year began with the bloody attack on Istanbul's Reina club which killed 39 people. It was later claimed by the militant Islamic State (IS) group.