(Recasts with killing of 14 kidnapped tribesmen)
BAGHDAD, Jan 16 (Reuters) - The bodies of 14 Sunni Muslim tribesmen were found in date palm groves north of Baghdad on Thursday, a day after they were kidnapped by uniformed men in security forces vehicles, Iraqi police and medics said.
The victims, all from the Albu Rawdas tribe, had been abducted while they were attending a funeral in the town of Tarmiya, 25 km (16 miles) north of the Iraqi capital.
When their relatives asked the security forces what had happened to them, they denied any involvement in their disappearance, the police said.
The motive for the killings was not immediately clear, but Sunni tribesmen opposed to al Qaeda have been targeted in a similar way in Tarmiya in the past. Such "Sahwa" militiamen helped U.S. troops turn the tide against al Qaeda from 2006 and are viewed as traitors by their hardline co-religionists.
Also on Thursday, a suicide bomber killed three pro-government Sunni tribesmen at a checkpoint 25 km west of the rebel-held city of Falluja, police said.
Assailants also planted bombs around the mayor's office in Falluja, destroying it completely. There were no casualties as the building was unoccupied at the time, the police said.
Al Qaeda-linked militants backed by Sunni tribesmen hostile to the Shi'ite Muslim-led government, seized Falluja, 50 km west of Baghdad, on Jan. 1 and have been locked in a standoff with Iraqi troops and tanks around the city ever since.
Prime Minister Nuri al-Maliki has ruled out a full-scale assault on Falluja, scene of some of the toughest battles fought by U.S. troops during their 2003-2011 occupation, but has called on tribes there to evict the militants themselves.
The militants and their allies overran Falluja after the government broke up an anti-government Sunni protest camp in the nearby city of Ramadi and arrested a Sunni opposition lawmaker in a raid in which his brother and five bodyguards were killed.
Iraq's minority Sunnis are divided. While most resent the policies of Maliki's government, many also oppose al Qaeda and some armed tribesmen are actively fighting the militants. (Writing by Alistair Lyon; Editing by Mark Heinrich)