Taliban militants raided a police headquarters in western Afghanistan, igniting clashes that killed four and raised fears of a new insurgent front, while Poland promised at least 900 troops to bolster a NATO-led security force.

The raid was the second bout of Taliban violence in two days in Farah province and came a few days after a roadside bombing there wounded four Italian soldiers.

Intense NATO-led operations targeting Taliban forces in the south have forced insurgents to flee north and west into calmer areas like Farah, NATO and Afghan officials say.

Canadian-led troops launched a major operation in Kandahar province's Panjwayi district on Sept. 2, killing at least 510 militants, NATO has claimed -- one of the most intense battles since U.S.-led forces ousted the Taliban regime in late 2001.

The alliance's top commander, U.S. Gen. James L. Jones, has called for 2,500 extra troops and air support to help continue such missions and end the Taliban threat quicker. But NATO members meeting in Brussels on Wednesday failed to commit more forces.

Poland's defense minister said his central European state will send at least 900 troops, suggesting they would be in place in February -- not immediately as NATO commanders on the ground have been pressing for, and not in the volatile south where they are most needed. Poland already has 100 troops in Afghanistan.

"As of February next year, over 1,000 Polish soldiers are going to be serving in Afghanistan," Radoslaw Sikorski told journalists Wednesday evening in Washington in the comments shown on Polish television Thursday.

"It will be a mechanized battalion that will be stationed at Bagram, where 100 of our soldiers are. We are going to take part in operations primarily in the eastern part of Afghanistan."

A NATO spokesman in Kabul said the 900 extra troops had long been expected to arrive in February as part of a routine transfer of NATO forces.

"We are looking at how this can be sped up," Maj. Luke Knittig said.

The early morning clash in Farah province raised fears that Taliban militants under NATO attack in southern strongholds of Kandahar and Helmand are relocating into previously calm areas in the west of the country.

Militants driving in dozens of pickup trucks and firing rocket-propelled grenades surrounded the police compound in the Farah town of Bakwa at about 3 a.m., said Maj. Gen. Sayed Agha Saqeb, the provincial police chief.

Taliban forces held the compound for about one hour before police reinforcements arrived to push the militants out of the town, Saqeb said.

Two policemen were killed and two wounded, while two Taliban died and four others were wounded, Saqeb said.

The clash came a day after Taliban insurgents ambushed another police patrol in Farah. Four police and four militants were killed.

"In some parts of Farah, we are seeing Taliban coming from Helmand and we are planning to attack them," Saqeb said on Wednesday. "But we need more transportation and telecommunications equipment."

NATO spokesman Maj. Toby Jackman said the alliance forces were aware insurgents could be fleeing toward Farah from fighting in Helmand and Kandahar.

"Bakwa is an area we have been monitoring extremely closely," Jackman said. "We did a search operation about a month ago because we are aware insurgents have been crossing there from the south and moving into the western areas."

"If there is the possibility of some sort of security deterioration in the area we will get onto it very quickly."

NATO has about 20,000 forces in Afghanistan, with almost half deployed in the south. Some 1,600 soldiers from a mix of nations operate in Farah.