Washington  - A key gauge of the US economy unexpectedly rose in December, the Conference Board said Monday, attributing the increase to a massive injection of cash into the financial system by the Federal Reserve.

The private New York-based group's index of Leading Economic Indicators climbed 0.3 per cent in December, as a surge in the real money supply offset drops in the housing sectors and more than 500,000 job losses in the month.

It marked the index's first gain in 6 months. The index evaluates 10 key areas of the economy and gauges activity over the coming 3 to 6 months. (dpa)