Rwandan forces used helicopter gunships and cannons in a counterattack that stopped rebels advancing on the central African nation's capital, a diplomatic source said Thursday.

The diplomat - speaking from Rwanda's capital, Kigali - said the rebel force had been sharply reduced by the army attack on the rebel's main force near Gabiro, 40 miles from Kigali."Frankly, the tide has turned," the diplomat said on condition of anonymity. "It's not looking good for the rebels," who invaded Rwanda from Uganda several days ago.

There were no reliable casualty reports. Diplomats in Kigali said the government was trying to move civilians out of the combat zone, a sparsely populated and relatively flat region.

Despite the offensive, a group of more than 100 guerrillas reportedly reached the shores of Lake Muhazi, 30 miles east of the capital, using hit-and-run tactics and sometimes moving in disguise, another diplomat said.

The rebels, whose numbers are estimated from several hundred to more than 1,000, invaded Rwanda from its northern neighbor Uganda on Sunday. They are seeking to overthrow the government.