Officials confirmed on Thursday that the Islamist fighters killed two Afghan army soldiers in Mizan district and took over government buildings near the provincial capital of Qalat in Zabul province.

But Zabul police chief Muhammad Ayub insisted Taliban controlled the district for less than two hours.

Ayub added that two fighters were also killed in a fierce skirmish on Wednesday.

Mizan district chief Rahmat Allah Shawalikotai also stressed that government troops were now firmly back in control.

The military commander of southern Kandahar province which borders Zabul, General Khan Muhammad, said troops had been sent to reinforce the area from Kandahar but refused to say how many for reasons of operational security.

Guerrilla war

Southern and southeast Afghanistan have been hit by a wave of violence in recent months, with Islamist fighters targeting government and military installations and in some cases attacking and killing foreign officials.

A similar attack in April left
government buildings destroyed

Most attacks against government targets involve guerrilla-style tactics with groups of Taliban targeting small numbers of opponents and then retreating.

On Thursday a bomb exploded near Afghanistan's border with Pakistan injuring a policemen and three civil servants, a United Nations spokesman said.

The blast occurred near Khost city, some 40kms east of the border with Pakistan's tribal regions, where al-Qaida and Taliban fighters are believed to be in hiding.

The three civil servants were employed by the Central Statistics Office, UN spokesman David Singh told a press conference.

Deputy commander of Khost's local military division Neshan al-Din Ahangar said the blast was caused by a newly-laid roadside bomb.