ISTANBUL (Reuters) - A Kurdish militant group once linked to the outlawed Kurdistan Workers Party (PKK) claimed responsibility on Friday for the bombing in the Turkish capital Ankara that killed 28 people this week, according to a statement on its website.

The Kurdistan Freedom Hawks (TAK) said the bombing was in response to the policies of President Tayyip Erdogan and said it would continue its attacks. It said the bomber was a 26-year old Turkish national born in the eastern city of Van.

The group most recently claimed responsibility for a mortar attack at Istanbul's second airport in December that left an aircraft cleaner dead.

TAK has in the past said its relationship with PKK militants has been severed. Both groups are regarded as terrorist organizations by Ankara and the United States.

A car laden with explosives was detonated next to military buses as they waited at traffic lights in the administrative heart of Ankara on Wednesday. The government has blamed the PKK and the Syrian Kurdish YPG for the attacks.

(Reporting by Ece Toksabay in Istanbul, Gulsen Solaker in Ankara; Writing by David Dolan; Editing by Nick Tattersall)