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Pakistan's government raised concerns Wednesday about a U.S.-led offensive in neighboring southern Afghanistan with visiting U.S. regional envoy Richard Holbrooke.

Islamabad is concerned the major U.S. offensive in Afghanistan's Helmand province ahead of elections there next month could push Taliban fighters across the border.

"We have some concern which we have been discussing with the U.S.," Foreign Ministry spokesman Abdul Basit said.

A senior Pakistani intelligence official said Islamabad has "reservations" about the Helmand offensive because militants crossing the border could destabilize Pakistan's province of Baluchistan, which for years has been facing a separate low-level insurgency by nationalist groups seeking more autonomy.

The official, who spoke on condition of anonymity because of the sensitivity of the matter, said Pakistani authorities had conveyed their concerns to the "appropriate quarters."

Pakistan's army has already beefed up its presence along the border in the area, and the official said authorities had not yet seen an influx into Baluchistan of militants from Afghanistan's Helmand province, where some 4,000 U.S. Marines launched an operation on July 2 against Taliban insurgents.

If a significant influx does occur, however, Pakistan may be forced to move troops over to the northwest from its border from India. But the official stressed that Islamabad cannot make that shift "beyond a certain point."

The Pakistani establishment still views India as its greatest threat. The two nations have fought three wars over the past six decades.

Pakistan shares a 1,600-mile (2,600-kilometer) rugged border with Afghanistan, inhabited on both sides by ethnic Pashtuns with strong family and clan ties who travel freely across the frontier. The section opposite Helmand is about 160 miles (260 kilometers) long and lies in Baluchistan.

Holbrooke said the U.S. was committed to coordinating with the Pakistani government in combatting militants.

"We want to be sure that we share with your government and your military, military plans so you can be prepared and coordinate because a lot of different things can happen here," Holbrooke said.

"The Taliban could move east into Baluchistan and cause additional problems, they could move west towards Herat, they could be trapped, and we have to be prepared," he said.

Pakistani forces are also wrapping up an offensive in the Swat Valley in the country's northwest, and have been carrying out strikes in nearby South Waziristan, part of Pakistan's lawless tribal belt along the Afghan border. The military is softening up the region ahead of an offensive aimed at eliminating Pakistani Taliban leader Baitullah Mehsud, the top commander of Pakistan's Taliban. Mehsud has been blamed for scores of suicide attacks and Islamabad considers him the country's greatest domestic threat.

On Wednesday, intelligence officials said Pakistani fighter jets destroyed two suspected militant hide-outs in South Waziristan, killing six men Tuesday believed to be associates of Mehsud. They spoke on condition of anonymity because they were not authorized to speak to the media.

It was not possible to independently confirm the strikes or casualty figures in the remote area, where access for journalists is restricted.

Prime Minister Yousuf Raza Gilani, who met with Holbrooke on Wednesday, reiterated Islamabad's objections to U.S. drone strikes in northwestern Pakistan, which target suspected top Taliban militants and al-Qaida leaders, saying they are counterproductive.

The strikes have "seriously impeded Pakistan's efforts towards rooting out militancy and terrorism from that area," Gilani's office said the prime minister told Holbrooke.

He also called on the U.S. to share intelligence with Pakistan and to provide equipment, ammunition and unmanned vehicle technology.

Pakistan already receives significant funding from the United States to arm its security forces and battle insurgents.