Around 1,000 Afghan soldiers are involved in the campaign

US troops and aircraft backed by 1,000 Afghan soldiers say they have attacked Taleban fighters in the Daychopan district of Zabul province, 300 kilometres (190 miles) southwest of Kabul.

A US military spokesman said between 70 and 100 enemy personnel had been killed since the start of the campaign.

The push has coincided with Pakistani military helicopters tightening security on their side of the border in what the Pakistani military says are routine exercises.

Taleban 'intrusion'

US military spokesman Colonel Rodney Davis said at Bagram airbase in Kabul that Operation Mountain Viper was continuing but that resistance in the past 24 hours had been "relatively light".

Afghan military and intelligence officials said 124 enemy fighters had died in the campaign along with five government soldiers and a US soldier who was killed in a fall.

Zabul intelligence director Khalil Hotak told the AFP news agency that coalition forces were now in charge of Daychopan and that there were no enemy forces in the area.

Coalition troops were pursuing fleeing Taleban from Daychopan into Mizan district, said the main Afghan commander in the area, Haji Saifullah Khan.

American forces are also carrying out an operation in neighbouring Paktika province.

The coalition campaign follows a series of raids by Taleban fighters against Afghan officials, police and aid workers in the south and east of Afghanistan.

On the other side of the border, a senior Pakistani security source told AFP that the military's helicopter exercises were "aimed at pre-empting any intrusion of Taleban into Pakistani territory".