An allegation that Iraqi police raped a Sunni woman while enforcing a new security plan in Baghdad has opened sectarian splits within the government.
The woman appeared for the media but kept her identity secret
The woman said she was assaulted at a police garrison on Sunday where she was falsely held for supporting insurgents.
Prime Minister Nouri Maliki, who is Shia, dismissed the claims, but senior Sunni officials insist it is true.
Observers say the row could undermine the security plan, in which mainly-Shia police are deployed in Sunni areas.
Mr Maliki accused "known groups" - taken to mean Sunni political parties - of fabricating the story, to discredit the security forces.
A series of attacks by insurgents around the capital has already shown the difficulties of trying to stem the tide of violence.
- A chemicals tanker was blown up in Taji, killing six and causing 148 people to inhale noxious fumes
- Two car bombs killed at least eight people and wounded 30 in south-west and south Baghdad
- A suicide bomber attacked a funeral in Baghdad, killing seven mourners
- Five US soldiers died in attacks on Monday, the military said.
The woman, whose identity has not been confirmed, made the rape allegation in an emotional interview with Arabic TV network al-Jazeera.
She was arrested in her Baghdad neighbourhood of Amil for helping insurgents and taken to a police facility where she claims she was assaulted by three officers.
Mr Maliki ordered an investigation into the case on Monday night, but cleared the three men hours later.
"Medical examinations showed the woman had not been subjected to any sexual attack," a government statement said.
"The prime minister has ordered that the honourable officers accused be rewarded," it added without elaborating.
But an aide of Vice President Tariq Hashimi, a Sunni, said the prime minister's office had acted in haste, and doctors had in fact confirmed rape had taken place.
The woman was named Sabrine Janabi by al-Jazeera, but Sunni politicians said this was not her real name.
The US military, whose medical staff oversaw the woman's examination, said it was aware of the various reports, but could not confirm anything.
Sunni politicians have accused the police of a series of human rights abuses perpetrated on their community and of turning a blind eye to attacks on them by Shia militants.