Former Iraqi spy chief, Farouk Hijazi, accused of plotting to assassinate former US president George Bush in the 1990s, was detained near Iraq's border with Syria, said a US official on Friday.

"He [Hijazi] is in custody and was picked up in Iraq near the Syrian border yesterday [Thursday] Iraqi time. I have no more details about the circumstances [of his arrest]," the US official, who requested anonymity, told Reuters.

Last week, Washington said it believed Hijazi was in Syria amid mounting accusations that Damascus was harbouring members of Saddam Hussein's government who had fled Iraq.

Earlier this week, in a sign that tensions were easing between the US and Syria, President George W Bush said Syria had taken some measures to seal its border. It was unclear whether Hijazi was captured with Syrian help.

Hijazi was director of external operations for the Iraqi intelligence agency in the mid-1990s, when the agency allegedly launched a failed attempt to assassinate Bush during a visit to Kuwait.

Hijazi subsequently served as Iraq's ambassador to Tunisia and Turkey.

Hijazi is among several high-level Iraqis taken into US custody over recent days. Also on Thursday, Tareq Aziz, Iraq's former deputy prime minister and one of the best-known figures in Saddam Hussein's old guard, surrendered to US forces.

US Central Command in Qatar and officials in Washington said that Aziz gave himself up to US troops in Baghdad and was 'under coalition control.'