MANILA, Philippines -- The peso sank to its lowest level against the dollar in nearly two years in early trading on Monday, forcing the central bank to intervene, traders said.

After ending at P48.991 to the dollar on Friday, the peso touched a 22-month low early Monday of P49.35, prompting the central bank to pump around $100 million into the market to ease foreign exchange volatility, traders said.

The peso had lost 20 percent of its value against the greenback since the start of the year. The unit ended 2007 at P41.52 to the dollar.

"If the central bank shows any weakness in its resolve (to intervene), expect the peso to fall further," a local bank trader told Dow Jones Newswires.

Traders put the dollar's next resistance level at P49.50.