CHICAGO, USA - A senior adviser to United States President-elect Barack Obama said on Monday the news that the US has been in a recession for a year underscored the need for an economic- stimulus package.

Mr Lawrence Summers, tapped by Mr Obama to become director of the White House National Economic Council, said the slump may be worsening.

'While the economy has already lost 1.2 million jobs this year, recent economic evidence suggests that the pace of this downturn is accelerating,' Mr Summers said in a statement.

'That is why President-elect Obama has set as his top priority passing an economic-recovery plan.'

The US arbiter of recessions said on Monday that the economy slipped into recession in December last year and that the downturn could be the worst since World War II.

Mr Obama has instructed his economic team to come up with recommendations for a stimulus package that would include a mix of middle-class tax cuts and spending on infrastructure projects.

House of Representatives Democrats are talking of a package in the range of US$500 billion (S$765 billion).