A mortar attack on Iraq's foreign ministry took place on Tuesday as visiting US Deputy Secretary of State John Negroponte was due to hold a press conference in the Green Zone compound, al-Jazeera satellite channel has reported.

Two mortar rounds had landed in the area. At least five people were injured in the incident.

The Foreign Ministry building is adjacent to the fortified Green Zone government and diplomatic compound, where the US embassy and Iraqi parliament are located.

Journalists were gathering for a news conference by Negroponte and Iraqi Foreign Minister Hoshyar Zebari when the blasts took place, al-Jazeera reported.

Negroponte has been in the country for several days and has held meetings with senior Iraqi officials to discuss a controversial pact that discusses the handover of security to Iraqi forces.

Iraqi political analysts told al-Jazeera TV that the blasts may have been a political message reflecting the rejection of some Iraqi militant groups to the security pact, known as the Status of Forces Agreement (SOFA).

Negroponte explained at the press conference that negotiations were at an "advanced stage." Differences between the two states remain over whether or not US troops will have immunity from prosecution for acts committed in Iraq, and on future troop command, amongst other issues.

A number of Iraqi politicians and lawmakers are also against the mandate, saying it will violate the country's sovereignty.

The long term agreement would lay down the legal basis for a continued US military presence in Iraq after a UN mandate expires in December.

However, after months of disputes and criticism, the United States and Iraq are working on a short-term "memorandum of understanding" instead.

During the press conference, held minutes after the attack, Zebari told reporters that progress is being made on the pact and that the US delegation has shown great flexibility in some issues of concern to the Iraqi.

While Zebari did not specify timing for the signing of the pact, he said that the move needs a courageous decision from Iraqi politicians.

Meanwhile the US army reported that one US soldier, one policeman and one militant were killed in a clash in the northern Iraqi city of Mosul, the scene of recent al-Qaeda related activity.

In the city of Kut, south east of Baghdad, US soldiers captured five members of an Iranian-backed Shiite militia group, the Hezbollah Brigades. The group has reportedly received anti-tank weapons from Iran, which have been used against US and Iraqi troops in the past week.