By JIM HEINTZ
Associated Press Writer

DUSHANBE, Tajikistan - Fighting between Afghanistan's opposition northern alliance and the ruling Taliban intensified Tuesday as the U.S. continued its airstrikes.

Taliban fighters and the alliance, a fractious union of ethnic groups and warlords, clashed along the Pyandzh River separating this former Soviet republic from Afghanistan. Tajikistan and Afghanistan share a 750-mile border.

Northern alliance spokesman Abdullah told CNN the rebels were stepping up the pressure. "The Taliban are in a really hard situation at this moment in northern Afghanistan," he said.

The primary front line between the Taliban and the northern alliance, which holds about 10 percent of Afghanistan's territory, is north of the Afghan capital, Kabul. Another hot spot is around the city of Mazar-e-Sharif, south of Afghanistan's border with Uzbekistan.

On Monday, the northern alliance said it was preparing a major offensive that would target key cities, including Kabul and the strategically located Mazar-e-Sharif. Capturing the city could give alliance fighters their first tangible success.

A top strategist for the anti-Taliban militia told The Associated Press on Monday by telephone from a base in the eastern Iranian city of Mashhad that the campaign could begin as early as Tuesday.

However, Russian TV reports from northern Afghanistan said Tuesday the alliance was waiting for U.S.-led strikes to target Taliban forces in the vicinity of the alliance's positions.

"I would say that sometime from now it will happen," Abdullah said.

That could prove tricky, because some Taliban forces have recently moved even closer to the alliance's lines precisely to avoid such airstrikes, Russian reports said.

Col. Abdul Qudussy, military attache at the Afghan Embassy in Dushanbe, said the opposition hoped to send its own planes to help attack the Taliban. Qudussy would not give details about the opposition alliance's air capacity, which is believed to be only a few aging aircraft.

The Russian border guards, who control the frontier for Tajikistan's weak armed forces, reported fighting throughout the night near Sherkhan, across from the Novobrazhnaya border post and near the town of Imam-Sakhib.

Rocket and artillery fire was heard, the press center of the Russian border guards said Tuesday. The border guards believe the Taliban are reinforcing the area with the goal of breaking through the Tajik border.

Sounds of increased fighting also were heard early Tuesday in Uzbekistan's border city of Termez. Residents said they heard bombs exploding; others said they heard artillery fire.

Since last week, alliance officials have reported defections by dozens of Taliban troops, but the reports could not be independently verified.

Meanwhile, Afghan refugees were flocking to the Tajik border. Tajikistan does not want Afghan refugees to enter its territory and is not allowing them to cross.

A Washington-based envoy for the northern alliance said 1,200 Taliban troops and 40 officers defected to the rebels, preventing the Taliban from using a major road near the Bagram air base north of Kabul. The figures could not be independently confirmed.

A U.S. official, speaking on the condition of anonymity, said the claim has not been verified, but defections of Taliban forces have been expected.

Haron Arin, the alliance envoy, said: "The great majority of the Taliban would prefer to stay alive."