UK Foreign Secretary Jack Straw has urged Iraqi leaders to put aside sectarian interests and form a government of national unity.
Mr Straw is meeting leaders for the second time in two months
December's election results show "no party, no ethnic or religious grouping can dominate" the Iraqi government, Mr Straw said on a surprise visit.
He is in Baghdad for talks with top politicians about the slow progress in forming a new coalition government.
Talks have faltered over splits within and between Shias, Sunnis and Kurds.
Shia leaders say they have the right to control key posts after winning 130 of the 275 seats in parliament.
But Sunni Arab leaders want to ensure they are represented at a senior level, and are seeking to break the control of Shia militias on the interior ministry.
The US has warned that aid to Iraq will be cut if the new government includes politicians with a strong sectarian bias.
The Iraqi prime minister dismissed the US warning.
Ibrahim Jaafari said he did not want a sectarian government, but would not accept interference in what was an "internal Iraqi affair".
"We do not need anybody to remind us, thank you."
Correspondents say Mr Straw's second visit to Baghdad in recent weeks illustrates UK and US concern at the difficulties faced in forming a government.
Following talks with President Jalal Talabani, Mr Straw told reporters Iraqis wanted a government that bound together different segments of society.
United Iraqi Alliance 10 seats short of a majority
Kurdistan Alliance again likely coalition partner
Sunni Arabs gain much greater representation
Secular alliances win fewer seats
Former PM Iyad Allawi's bloc loses half its seats
Deputy PM Ahmed Chalabi's alliance wins no seats
"International communities like us who played a role in liberating Iraq have a vested interest in a democratic, stable Iraq," he said.
On Monday, US ambassador Zalmay Khalilzad said aid could not be used to build up security forces run by people with a sectarian agenda.
The US official added that it was time for Iraqis to form a government that was not dominated by Shia Muslims and Kurds.
In the latest violence, a spokesman for a Sunni Arab political group has been found dead with multiple gunshot wounds, three days after his disappearance.
Sunni Arab leaders accuse the Shia-led interior ministry of employing militias to oppress their civilians under the guise of fighting the insurgency.
Mainly Sunni insurgents have launched tens of thousands of attacks on US forces, their allies and targets associated with the new regime established since the US overthrow of Saddam Hussein nearly three years ago.
Mr Straw's trip comes amid tensions between the British and Iraqi authorities in the south of the country.
Two regional councils have halted co-operation with the British army after a video showed apparent abuse of civilians by UK troops two years ago.
Mr Straw said the incident was under investigation and that there had been very few allegations of abuse overall.
Three soldiers have been questioned over the pictures and UK military police have interviewed four Iraqi youths.
Mr Straw's spokesman said there were no plans on this trip for the foreign secretary to visit Basra, where British troops are on patrol.