US Attorney General John Ashcroft is in intensive care because of a painful illness that involves inflammation of the pancreas, the US Justice Department said.
Mr Ashcroft (61) who became the top US legal officer in 2001 after a bitter confirmation battle following his appointment by President George W Bush, was suffering from a severe case of gallstone-caused pancreatitis, spokesman Mr Mark Corallo said.
"He was admitted to intensive care for careful monitoring and is being treated with antibiotics," Mr Corallo said.
Justice Department officials said Mr Ashcroft was expected to be in the hospital for at least four or five days, and that he then could face surgery.
Mr Ashcroft has been a target of criticism by civil liberties groups and some Democrats in Congress over the Bush administration's anti-terrorism policies adopted after the September 11, 2001, attacks.
Mr Ashcroft has defended the policies as necessary to prevent another attack and has strongly supported a sweeping anti-terror law that gave the government the power to tap phones, track Internet usage and mobile phones and detain immigrants.
The illness usually begins with pain in the upper abdomen, and Mr Ashcroft initially thought he had stomach flu, Mr Corallo said.
"Acute pancreatitis can be a severe, life-threatening illness with many complications," it said in its information clearinghouse on digestive diseases.