US Attorney-General Alberto Gonzales has resigned, an official said, ending a controversial tenure as chief law enforcement officer that blemished the administration of President George W Bush.

The official confirmed a Web site report of the resignation by The New York Times, telling Reuters an official announcement would be made later in the day.

The 51-year-old Bush loyalist was at the center of a political firestorm over the sacking of federal prosecutors last year, which critics in Congress complained were politically motivated.

The official told The Times that Gonzales had told Bush on Friday in a telephone call that he would resign. The official said the job would not be open for long.

Gonzales worked for Bush when he was governor of Texas in the 1990s. He served as White House lawyer in Bush's first term as president before becoming the first Hispanic attorney general in February 2005.

Current and former administration officials had said the department's integrity had been damaged under Gonzales with controversy over the firing of the prosecutors, his support for Bush's warrantless domestic spying program and other issues.

They said as a result employee morale had been hurt and Gonzales' relations with the Democratic-controlled Congress had deteriorated beyond repair in a firestorm of criticism from lawmakers, including some Republicans.

Several senators had said they had lost confidence in Gonzales and his ability to head the Justice Department. Reuters