Afghan opposition forces said Thursday they were advancing steadily toward the key northern city of Mazar-e-Sharif with the help of round-the-clock U.S. bombing. The ruling Taliban, however, said they pushed back several opposition attacks.

Both sides said fighting was intense south of Mazar-e-Sharif, which the Taliban seized from the opposition northern alliance in 1998. An opposition victory would allow it to open a supply corridor from Uzbekistan and direct troops toward Taliban strongholds further south.

U.S. jets also struck targets Thursday afternoon along the front lines north of the capital, Kabul, bombing Taliban positions around the town Qarabagh and three other Taliban-controlled villages.

Gen. Tommy Franks, commander of the anti-terrorism campaign in Afghanistan, said Thursday that the United States is interested in Mazar-e-Sharif because it could provide a land bridge to Uzbekistan. Humanitarian and other supplies could move along that route, he said.

"I have seen reported by many in the media that this is a great gunfight going on in the vicinity of Mazar-e-Sharif," he said. "It's a bit early for us to characterize this as the success .. but yes, there is a big fight going on in the vicinity."

The Pakistan-based Afghan Islamic Press reported that warplanes conducted 27 bombing raids in the western province of Herat and targeted the southern city of Kandahar, the Taliban headquarters.

North of Kabul, witnesses said U.S. jets and at least one B-52 bomber dropped dozens of bombs on Taliban lines. Opposition spokesman Bismillah Khan said there were no immediate plans for an offensive in that area.

Huge plumes of smoke billowed from Taliban positions, which did not fire anti-aircraft guns as they have on past bombing runs. It was unclear whether the guns had been knocked out or whether the Taliban were saving their ammunition.

Most of the military activity, however, has now shifted to the far north of the country around Mazar-e-Sharif and northeastern Takhar province on the border with Tajikistan.

Pentagon officials reported Wednesday that the opposition northern alliance appeared to be making gains south of Mazar-e-Sharif in fluid and chaotic fighting, in which anti-Taliban troops charged tanks and armored personnel carriers on horseback.

Mazar-e-Sharif is believed to have a population of about 200,000, although the figure is an estimate since many people were believed to have fled when the Taliban seized the city three years ago.

There are no working telephone links to the city and it is difficult to determine conditions there since the fighting escalated.

Marine Corps Gen. Peter Pace, vice chairman of the Joint Chiefs of Staff, said U.S. special forces troops are with opposition units coordinating airstrikes, which alliance commanders said helped them breach some Taliban defenses south of Mazar-e-Sharif.

Speaking Thursday by satellite telephone, opposition spokesman Ashraf Nadem said his forces had captured another district, Sayyat, southwest of Mazar-e-Sharif.

The Taliban denied losing the district and told the Afghan Islamic Press that three opposition attacks south of Mazar-e-Sharif had failed.

The Taliban's Bakhtar news agency said the northern alliance was still 15 miles south of Mazar-e-Sharif and that opposition claims that they were within four miles were false.

In Pakistan, a group that wants to separate Kashmir from India, Harkat-e-Jehad-e-Islami, said 85 of its fighters were killed by U.S. bombs while fighting alongside the Taliban near Mazar-e-Sharif.

The statement could not be independently verified. The Islamic militant group is one of several that are fighting against Indian forces in Kashmir. Some of them have maintained close ties with the Taliban.

Bakhtar claimed U.S. jets also bombed Kunar province east of Kabul, killing three civilians and injuring six people Wednesday. An empty school was also flattened, it said.

In northwest Kabul, residents said a rocket slammed into one home Wednesday night, killing a couple married just two months ago. Pillows, clothes and the young bride's belongings were strewn about the destroyed home.

"Why did they do this?" the young woman's grandmother sobbed. "Find your enemies. But why are you killing us?"

The reports could not be independently verified. The Pentagon has denied Taliban claims that more than five weeks of bombing have inflicted widespread civilian casualties.

Along the Kabul front, Khan, the opposition commander, said U.S. bombing there overnight had been "very effective," and that two Taliban tanks and an anti-aircraft position were destroyed.

Most front-line Taliban installations have been destroyed and Taliban troops were moving around to evade U.S. bombs, Khan said.

Meanwhile, the Afghan Islamic Press also reported that the Taliban have arrested 16 Afghans on suspicion of spying for the United States. An unidentified Taliban intelligence official told the agency that the suspects included Abdul Manaf, a former Afghan army colonel.

Pakistani President Pervez Musharraf was in France Thursday on his first international trip since Sept. 11. Musharraf, who planned to travel to Britain and the United States as well, has backed the U.S.-led anti-terrorism campaign, despite opposition from Muslim groups at home.