US President George W Bush has delivered a strong warning to Congress not to limit the powers of the head of a new Department of Homeland Security, clearly indicating he will veto a measure now before the Senate.

I'm not going to accept legislation that limits or weakens the president's well-established authorities when it serves our national interest

President George W Bush

The warning came a day after the Senate Governmental Affairs Committee approved a bill that would deny Mr Bush the power to limit labour rights for the department's 170,000-strong workforce.

''A time of war is the wrong time to weaken the president's ability to protect the American people," Mr Bush said.

The Democrat-sponsored Senate version of the bill does not exempt the new agency from civil-service and budgetary rules - a move the Democrats claim is aimed at protecting workers' rights.

Hire and fire

However, Mr Bush rejected ''as strongly as I can state it'' the suggestion that his position was anti-labour.

''I'm not going to accept legislation that limits or weakens the president's well-established authorities when it serves our national interest," he said.

This bill gives the president about 90% of what he asked for

Bill sponsor Senator Joseph Lieberman

The president believes the legislation does not have enough managerial flexibility, particularly more authority to hire and fire.

However, few on Capitol Hill believe Mr Bush will not get his new department, one way or another, before Congress adjourns this autumn.

''There are differences, but I would say they are at the margins," said Joseph Lieberman, the Democrat who sponsored the Senate version.

''This bill gives the president about 90% of what he asked for."