Baghdad: A senior aide to Iraq's top Shiite cleric Grand Ayatollah Ali Al Sistani said the government should “be careful'' as it negotiates a long term security deal with Americans.

The agreement is aimed at replacing the current UN mandate for foreign troops in Iraq.

"The agreement...should secure the interests of the Iraqi people and not the opposite because the coming generations will be committed to it," said Abdul Mahdi Al Karbalaie.

Foreign Minister Hoshyar Zebari has said the first round of talks on the agreement would begin on February 27, although the US Embassy in Baghdad said no date has been set.

David Satterfield, senior adviser to US Secretary of State Condoleezza Rice, insisted negotiators would not seek a permanent presence in Iraq.

He also said attacks using armour-piercing roadside bombs the US says come from Iran have "increased significantly" this year.

"We believe that Iran wishes to see the forced departure of foreign forces—particularly US forces—in the most humiliating and devastating manner possible," he said.