The cleric al-Awlaki, who is a US citizen, is being targeted for his involvement in planning attacks on the US [Reuters]

A federal judge has dismissed a lawsuit by the father of Yemeni-American Islamic cleric Anwar al-Awlaki challenging the US government's controversial targeted-killing programme.

In a ruling issued on Tuesday, John Bates, the US district judge, said the father's suit seeking to block Barack Obama, the US president, from ordering the extrajudicial killing of his son "lacks standing".

Bates also said "his claims are non-justiciable," or incapable of being settled by a court, requiring dismissal of the case.

"The serious issues regarding the merits of the alleged authorisation of the targeted killing of a US citizen overseas must await another day or another [non-judicial] forum," Bates concluded in his 83-page ruling.

'Green light to kill'

The lawsuit was filed by civil liberties groups on behalf of al-Awlaki, a US citizen who joined al-Qaeda in Yemen and has been tied to plots against the United States.

Obama administration officials have refused to officially confirm that the "capture or kill" programme exists against Awlaki, although US officials have said the Central Intelligence Agency (CIA) has been given the green light to assassinate him, or to bring him to justice.

The cleric, who was born in New Mexico and lived in Virginia until leaving the country shortly after the September 11, 2001, attacks, has been sought by Yemeni authorities, who also want to capture or kill him.

US officials have described al-Awlaki as having a leadership role in al-Qaeda in the Arabian Peninsula, or AQAP, the group the US says was behind the recent thwarted attempt to target US-bound planes with package bombs as well as the botched attempt to bomb an airplane on Christmas Day in 2009.

AQAP has claimed responsibility for the plots.

Awlaki has been linked to other attacks, including that carried out by Major Nidal Malik Hasan of the US Army at the Fort Hood base in Texas in November 2009.

US officials have warned that Yemen is becoming a safe haven for al-Qaeda fighters.