By Jonathan Paye-Layleh Monrovia reporter

Liberian rebels of the Liberians United for Reconciliation and Democracy, or Lurd, have killed at least 15 people in the north-west of the country.

Military sources have told the BBC that the attacks, involving logging trucks and a military jeep, took place in a 45-kilometre-stretch of road between the diamond rich towns of Lofa Bridge and Gbarma.

In one incident a truck travelling with an unspecified number of civilians was ambushed on their way to the timber station of a logging company.

Scores of people are still missing.

Investigation

There are reports of fighting between the Lurd rebels and government troops in the Zorzor district on Liberia's northern border with Guinea.

Liberia's Defence Minister Daniel Chea said investigation was under way into circumstances surrounding the ambushes.

The rebels have intensified their activity in the north of the country, prompting President Charles Taylor to declare a state of emergency last month.