Kabul - An attack in western Afghanistan Thursday marked the beginning of a new countrywide offensive by the Taliban aimed at countering the arrival in the coming months of US and NATO reinforcements, the Islamist rebels said.

Mullah Brodar, deputy to Taliban supreme leader Mullah Omar, said the new operation, dubbed Nasrat, which means victory, is similar to the Taliban's spring offensives in previous years and would include an increased number of suicide attacks, ambushes and offensive assaults.

The new operation got under way with Taliban militants attacking the Salemi police post in the Pashtun Zarghoon district of Herat province, Qari Mohammad Yousif Ahmadi, a Taliban spokesman, said in a statement posted at the rebels' website.

He claimed that six security officers were killed and the commander of the post, who was wounded in the attack, fled the area before the militants torched the station.

Abdul Raouf Ahmadi, a police spokesman in western Afghanistan, confirmed the attack but denied the Taliban's casualty figures, saying four police officers received minor injuries in the rocket attack.

Ahmadi said the police forces inflicted casualties on the Taliban side during the three-hour gunbattle but could not give any figures.

Taliban militants have steadily gained strength in Afghanistan in the past three years after the ouster of their ultra-Islamic regime in late 2001, and they extended their territory to larger swaths of the country last year.

Compared to the eastern and southern parts of the country, where Taliban-led insurgents are most active, western and northern provinces are relatively peaceful. But under their new offensive, the Taliban vowed to move their battleground into new areas of the country.

A suicide attack and ambush was carried out in the northern province of Kunduz Wednesday, killing one German soldier and wounding nine. The Taliban claimed responsibility for the bombing.

With the deployment of 21,000 additional US soldiers and around 5,000 NATO forces, there would be more than 90,000 international troops deployed from 42 nations in Afghanistan by this summer.