Two US soldiers have been killed and 13 wounded in separate attacks in Iraq as the interim Iraqi prime minister insisted violence was receding after the assault on Falluja. The two US soldiers were killed in a roadside bomb attack on their convoy in the Baghdad area, capping one of the deadliest months for the US military since the start of the war in March 2003. The latest fatalities brought to 125 the number of US soldiers killed since 1 November. Four UK soldiers were also killed in the period. Nearly a week into Operation Plymouth Rock, launched by US marines, British troops and Iraqi forces in the area south of Baghdad, two marines and three anti-US fighters were killed on Sunday. Thirteen US marines and two civilians were also wounded when mortar shells struck a military base south of Baghdad, a marine spokesman said. In a related incident, four Iraqi national guardsmen were killed in an attack in the town of Baghdadi in al-Anbar province. "A car bomb exploded near a national guard checkpoint, killing four members of this force and wounding three more," a police source said on Monday. The attack occurred in the same town in the province of al-Anbar where 10 policemen were killed in a car bomb attack a month ago. **Fighters arrested*** Captain David Nevers from the 24th Marine Expeditionary Unit said at least three anti-US fighters were killed in separate incidents, as US-led forces continued their sweep of the area, which had become a no-go zone in recent months and made any trip south of Baghdad extremely perilous. Thirty-two suspected Iraqi fighters were detained on Sunday, bringing to more than 180 the number of people held since the start of the operation. The operation to control the area followed from the massive assault launched on 8 November on the western city of Falluja. US-led forces moved on Falluja in the largest military operation since the 2003 invasion, in a bid to remove what was seen by the US military and Iraq's interim government as one of the main obstacles to holding viable polls in January. In continuing operations in the western Iraqi province of al-Anbar, which includes Falluja and the town of Ramadi, three US servicemen were killed on Sunday, reported an AFP journalist embedded with US troops. **Falluja assault*** He also said two others were killed on Friday in the same province. The US military could not immediately release details of the circumstances of the deaths. Nevertheless, interim Prime Minister Iyad Allawi insisted on Monday that the general level of violence had dropped since Falluja had been taken. "The level of criminal operations has receded and is continuing to drop following the operation in Falluja," he said on the state-owned Iraqiya television, in response to questions from viewers. On Friday, several major Iraqi parties had argued that security conditions did not allow the organisation of viable polls across the country and called for a six-month delay. But most of the relevant authorities rejected the idea and said everything would be done to hold the elections on 30 January, as scheduled. **US army blocks aid convoy for Falluja*** The US military has prevented an aid convoy from reaching the besieged city of Falluja, a doctor based in Baghdad who accompanied the convoy says. "The Iraqi ministry of health asked us to go to Falluja. When we were on our way, the US army stopped our convoy, and carried out a search," said Dr Ibrahim al-Kubaisi. "After we waited in the US base, located near Falluja, for four hours, a doctor told us that they had agreed with the Iraqi ministry of health to send a medical team to Falluja but only after eight or nine days. "There is a terrible crime going in Falluja and they do not want anybody to know. I transferred four injured people from the Jordanian field hospital to a hospital in Baghdad. **Chemical Weapon Used in Falluja*** "They told me that there is a crime in there; chemical weapons are being used. The corpses don't have traces of gunshots but black patches. "US forces allow people to go into al-Hadra al-Muhammadiya area, in Falluja, but they prohibited anybody to enter al-Julan, al-Askari and al-Senai neighbourhoods. "There are Iraqi families under siege in there," the doctor said. The humanitarian situation for Falluja residents has been reported to be dire. Thousands of Falluja residents have fled the city and are living in makeshift shelters surrounding the city. **Elections*** "Postponing the elections is out of the question," electoral commission chairman Abd al-Husayn al-Hindawi said on Saturday after examining a request by 17 organisations, including 10 major parties. Opponents of a delay argue that the current US-appointed administration's lack of legitimacy is one of the factors fuelling support for anti-US attacks. They add that there is no guarantee security conditions will be better in six months. Meanwhile, the country's main economic lifeline came under threat again when a pipeline between two major refineries was attacked. A source at the Baiji refinery - which provides power for large swathes of northern and central Iraq - said the flow of oil in the damaged pipeline had been slashed by 80%. On Sunday, a pipeline between the Rumaila oilfields and the Basra terminal - which accounts for the bulk of Iraq's exports - was also damaged but production was not affected, said the South Oil Company. **PHOTO CAPTION*** US soldiers examine the scene after an US military truck was damaged in car bomb attack on Baghdad's airport highway Tuesday Nov. 30, 2004. (AP)