ANKARA (AFP) - The Turkish authorities on Saturday released without charge a man who was carrying a fake bomb outside the prime minister's office, local media reported.

The man, identified as Tugrul Bayir and previously described by officials as "mentally unstable", was freed after questioning as he has no prior criminal record, the private NTV television network said.

The 52-year-old caused a security scare in the capital on Thursday when he attempted to breach a security barrier outside the office of Prime Minister Recep Tayyip Erdogan in central Ankara's Kizilay district.

Mr Erdogan was not in his office at the time.

Officials had said security guards wrestled him to the ground and only fired shots into the air, contrary to initial media reports that the man was shot and wounded.

Local media reported that Bayir, who has debts amounting to 35,000 Turkish lira (S$21,800), took such action to draw attention to his plight.

In the past, Kurdish rebels or extreme left-wing groups have claimed attacks in Turkish cities.

In February this year, a suicide bomber attacked the United States Embassy in Ankara, killing himself and an embassy security guard.

The radical Revolutionary People's Liberation Front (DHKP-C), designated a terrorist organisation by the United States, claimed the attack.