Romania has expelled five Iraqi diplomats for conducting activities "incompatible" with their status the Foreign Ministry has said.
Around 4,000 US troops are currently based in Romania
A statement from the ministry said that the presence of the diplomats had become "undesirable".
Romania's Prime Minister, Adrian Nastase, confirmed the move but denied it was because of pressure from the United States.
The US has expelled two Iraqi diplomats in the United Nations.
It has identified a further 300 Iraqis in 60 countries - some of whom are diplomats - and has called on governments to expel them, arguing the alleged agents could attack US interests.
Australia has also ordered an Iraqi diplomat it accused of being an intelligence agent out of the country.
"Our secret services are attentively surveying the movements of personnel from the Iraqi embassy in Bucharest, and in certain cases there have been problems," Mr Nastase was quoted by French news agency AFP as saying.
Romania recently closed its embassy in Baghdad and removed its personnel because of growing fears of a military conflict in Iraq.
A staunch supporter of US hardline policy towards Iraq, the government has offered Washington non-combat troops and use of its air and military facilities.
Around 4,000 US soldiers are also currently stationed in a military base in the Black Sea town of Constanta ahead of a possible war in the Gulf.