The bodies of the 11 Ukrainian citizens who died when a passenger plane was accidentally shot down by Iran this month have returned to Ukraine.

President Volodymyr Zelenskyy looked on on Sunday as coffins draped in the country's flag were carried from a Ukrainian military plane to a waiting hearse at Boryspil International Airport, east of the capital, Kyiv.

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Relatives came to the airport carrying bunches of flowers while airline staff, some in tears, were waiting on the tarmac. Prime Minister Oleksiy Goncharuk and other officials also attended the solemn ceremony.

The funerals are expected to be held on Monday.

All 176 people on board the Ukraine International Airlines Flight 752 from Tehran to Kyiv were killed when the Boeing 737-800 was shot down on January 8 at a time of high tensions between Iran and the United States.

Most of those on board were Iranians or dual nationals. Fifty-seven Canadians were among those killed.

At the ceremony in Kyiv on Sunday, soldiers held up flags representing the different nationalities of those who died.

Pressure mounting on Iran

Meanwhile, Iran on Sunday denied earlier reports that a decision had been taken to send the plane recorders to Ukraine.

"We are trying to read the black boxes here in Iran. Otherwise, our options and Ukraine and France, but no decision has been taken so far to send them to another country," Hassan Rezaifar, a director in charge of accident investigations at Iran's Civil Aviation Organization, told Iran's IRNA news agency.

Al Jazeera's Dorsa Jabbari, reporting from the Iranian capital, Tehran, said Iran's investigations continue with the assistance of officials that have come to Iran from Germany, France, Ukraine and Canada.

"We also know that of the 176 bodies, 150 bodies have been returned to their families and loved ones. There's 10 bodies that the Iranians say they have not yet identified because they don't have enough information for the time being," she said.

Jabbari added that German airline Lufthansa had extended its ban on flights to Iran until mid-March, after initially announcing it would suspend flights to the country until the end of January.

The plane disaster and the delay in admitting responsibility sparked protests in Iran and added to international pressure on the country as it grapples with a long-running dispute with the US that briefly erupted into tit-for-tat attacks this month.

It was mistakenly shot down just hours after Iran launched missiles at Iraqi bases housing US troops in response to the killing of top Iranian general Qassem Soleimani in a US drone strike in Baghdad.