The rebels say their offensive is aimed at forcing the elected government of President Ahmed Tejan Kabbah to negotiate a political settlement. Their demands include the release from prison of a key rebel leader, Foday Sankoh, who was sentenced to death in October for treason.

Sierra Leone expert Stephen Ellis: Fighting has not ceased since the coup

Foday Sankoh is accused of collaborating with the former military government, which took power in a coup in May 1997, and was forced to flee by the West African intervention force, Ecomog, in February 1998.

The ousting of the military government led to big celebrations in the capital, Freetown and the return from exile of Sierra Leone's civilian president, Ahmed Tejan Kabbah.

Ecomog said at the time that it was conducting mopping up operations against the remnants of the military government in the diamond-rich areas of the east of the country.

Rebels regrouped

But in fact, the soldiers of the Armed Forces Revolutionary Council (AFRC) and their allies in the Revolutionary United Front (RUF), had merely retreated into the bush, and were regrouping.

The RUF - led by Foday Sankoh - first took up arms in 1991, emerging out of the civil war in neighbouring Liberia.

For several years, it fought against the Sierra Leonean army. But at the time of the military coup in May 1997, the RUF joined forces with the AFRC and they have remained allies ever since.

Brutal tactics

The rebels are believed to enjoy the support of Liberia - though the government there denies this. The rebels' tactics have been brutal in the extreme - one recent offensive was code-named Operation No Living Thing.

Thousands of Sierra Leoneans have had limbs cut off by machete in a campaign of terror designed to deter villagers from supporting the government.