KABUL, Afghanistan — Pressure was mounting yesterday on Britain’s European allies to commit ground troops to southern Afghanistan amid the fiercest fighting experienced in the country since the fall of the Taliban regime.

Operation Medusa, which is understood to be the first brigade-level battle NATO has fought in its history, appeared to be entering a critical stage after several days of engaging the enemy.

Up to 700 Taliban fighters were alleged yesterday to be pinned down by NATO and Afghan forces in an area around the village of Pashmul, southwest of Kandahar.

As NATO’s most senior civilian and military leaders arrived in the country, diplomatic sources said France, Germany, Italy, and Turkey were all being courted to contribute troops to combat operations in the south.

“The message is that troops for the south is the next priority,” one senior diplomat in Kabul said after the arrival of NATO’s Secretary General, Jaap de Hoop Scheffer, and its military commander, General James Jones. “We need the Turks, not least to show that this is not infidels fighting Islam.”

Many nations with forces in Afghanistan have previously included caveats that prohibit their forces from being sent to areas of high risk. Germany has 2,800 soldiers in Afghanistan but has caveats limiting their operations to the north. NATO can deploy them elsewhere only “under exceptional circumstances and on a temporary basis.”

But with British, Canadian, and Afghan forces taking ever-greater casualties as they attempt to flush out pro-Taliban forces, the case for bringing NATO allies into the battle has strengthened.

About 50 Taliban were reported to have been killed during fighting yesterday, in addition to 200 killed during the first three days of the operation.

A Canadian military spokesman in Kandahar, Major Quentin Innes, said: “We are using direct and indirect fire to pick them off as we see them moving. There was an attempted break out to the south by around 100 fighters this afternoon. They ran into a U.S. special forces unit leading to a three-hour firefight.”

Operation Medusa includes troops from Canada, America, Denmark, and Holland. British troops are involved in a supporting role and British Harrier jets provide close air support.

Fourteen British servicemen were killed when their Nimrod reconnaissance aircraft crashed on Saturday, while five Canadians have been killed, one to a “friendly fire” accident.

Concern that the Taliban force would be able to regroup and bring reinforcements to the battlefield was heightened Monday when Pakistan signed an agreement with pro-Taliban Islamic militants operating on the Afghan border.

The deal, which will lead to a cessation of Pakistan’s military offensive in the tribal agency of North Waziristan, signaled that its recent campaign to destroy border havens used by insurgents operating in Afghanistan had ended in compromise.

The area, believed to be home to Al Qaeda operatives, is where 80,000 troops have been deployed as a key element of President Musharraf’s commitment to the American-led war on terror.

Reports conflicted as to whether the accord has already been formally signed, but Pakistani officials said the deal would be formally announced by tomorrow.

However, hundreds of troops were already withdrawing from posts in the area.