Turkey's prime minister, Tayyip Erdogan, has said he will ask the United States to extradite an Islamic cleric he accuses of plotting to topple him and undermine Turkey with concocted graft accusations and secret wire taps.

Following questions after an AKP Party meeting on Tursday, Erdogan said that the process of extradition "will begin" against Fethullah Gulen, according to the Reuters news agency.

Gulen has lived in self-imposed exile in Pennsylvania since 1997 when secularist authorities raised accusations of islamist activity against him.

He denies engineering a police graft investigation but has denounced Erdogan over moves to shut down the inquiry by purging police and judiciary of his followers.

In an interview with PBS talk show host Charlie Rose broadcast late on Monday, Erdogan said Gulen, a former ally with broad support in the police and judiciary, could also pose a threat to US security by his activities.

"These elements which threaten the national security of Turkey cannot be allowed to exist in other countries because what they do to us here, they might do against their host,"Erdogan told Rose in the interview, according to a transcript.

He said Turkey had cancelled his passport and that he remained in the US on a green card as a legal resident.

Source: Reuters