Washington - An estimated 1.1 million people have joined the US jobless rolls over the past year, resulting in a rise in the unemployment rate to 5.1 per cent in March, the US government said Friday.

The figure adds another piece to the overall contracting economic picture in the country.

Earlier this week, US central bank head Ben Bernanke said a US recession was "possible" in the first quarter of 2008.

The unemployment rate in February was 4.8 per cent.

Economic growth in the last quarter of 2007 was 0.06 per cent.

The US Department of Labour said payroll employment had declined by 232,000, particularly in the construction, manufacturing and employment services branches.

Hispanic workers, who have a large presence in the construction industry, were most affected, with an unemployment rate of 6.9 per cent compared to 4.6 per cent for adult men and women.

The number of unemployed rose by 434,000, to 7.8 million. Compared to a year ago, the unemployment rate has risen by 0.7 percentage points. (dpa)