WASHINGTON (AFP) - United States Defence Secretary Chuck Hagel was sworn in Wednesday after a divisive Senate debate over his nomination that signals a rocky road ahead as he tackles deep budget cuts and frayed ties with Congress.

Mr Hagel, 66, took his oath of office at about 8:30 am (8.30pm Singapore time) at the Pentagon as his wife looked on, becoming the first combat veteran from the Vietnam conflict to take up the post.

Despite the bitter atmosphere that prevailed at his confirmation hearing, in which the ex-senator was pummelled by his former Republican colleagues over his statements on Israel and Iran, officials said Mr Hagel would focus on the work at hand and seek to cooperate with Congress.

"Senator Hagel has signalled his very strong commitment right away to get down to business, to get deeply invested in the work of the Pentagon and its military and civilian workers," Pentagon spokesman George Little said Tuesday.

"His goal is to look to the future." After a bruising Senate confirmation hearing and a 10-day delay engineered by Republicans, senators voted 58-41 to approve Mr Hagel for the post previously held by Leon Panetta.

Although his opponents failed in the end to derail his nomination, their hostile stance signalled that Mr Hagel will not be afforded much breathing room when it comes to working with Congress, without the kind of bipartisan support his predecessors enjoyed.

Within 48 hours of being sworn in, Hagel will confront steep automatic budget cuts of roughly US $57 billion which are due to kick in Friday due to political deadlock in Congress.