Sixteen Turkish workers who were abducted four weeks ago by men wearing military uniform in Iraq have been released and flown back home.

A Turkish plane carrying the workers from the Iraqi capital Baghdad landed on Wednesday at an Ankara airport, where they were embraced by their relatives.

The men were among 18 employees of major Turkish construction firm Nurol Insaat abducted on September 2 in the Sadr City area of north Baghdad, where they were working on a football stadium project.

Two were released in the southern city of Basra two weeks later.

The release of the other 16 had been expected after a video in which the kidnappers said their demands had been met was posted online on Sunday.

Prime Minister Ahmet Davutoglu broke the news about their release on Twitter early in the day.

"Our 16 workers have just been received by our Baghdad ambassador. I talked to some of them on the phone," he wrote.

"Thankfully, they are in good health and are preparing to return [home] as soon as possible," he said.

Conditions for release

The group that captured them had demanded that Turkey halt the flow of fighters into Iraq, lift what it called a "siege" on Syrian Shia villages and stop the passage of oil from Iraq's northern Kurdish region via Turkey in defiance of Baghdad.

Of the three demands, the one about military developments in Syria appears to have been the key factor in the negotiations.

A deal was reached last week for a truce in an area where Syrian regime forces backed by Lebanon's Hezbollah group have been battling Sunni Muslim rebels.

The agreement provides for the evacuation of the Idlib province villages of Fuaa and Kafraya whose residents are Shias and had been besieged by rebels, including groups Turkey is perceived as having an influence over.

Ankara's ambassador in Baghdad, Faruk Kaymakci, told the AFP news agency the hostages were released south of the capital on Wednesday morning.

"I can confirm they were released, around 60 kilometres south of Baghdad, on the road to Karbala," he said.

Last year, 46 Turkish citizens were seized by the Islamic State of Iraq and the Levant (ISIL) group in Mosul, but were released unharmed after more than three months in captivity.

Source: Agencies