Pakistani security forces backed by helicopter gunships have launched an operation against tribal rebels in the troubled province of Balochistan.
Army spokesman Gen Shaukat Sultan told journalists the operation was targeted exclusively at "miscreant hideouts".
There are unconfirmed reports of casualties from Kohlu, a town 220km (135 miles) south-east of Quetta.
The operation follows rocket attacks last week on military camps and army officers in the area.
Gas-rich Balochistan has seen months of violence as tribal groups push for greater political and economic rights.
Balach Marri, a provincial MP for the Kohlu area, said he had reports that a number of people had been killed in the raids - although he could not confirm the exact number.
"The army has arrested hundreds of innocent people in the operation, which is still going on, and in which jet fighters and helicopter gunships are participating," he told the Associated Press news agency.
Local residents say security forces carried out aerial attacks on targets in the Jindran, Tilli and Pir Mahmood areas of Kohlu district.
Gen Shaukat Sultan denied there had been raids on villages, and said he had no details of any casualties.
"It is only their [militant's] camps that are being targeted," he said.
Meanwhile, the BBC's Aziz Khan in Quetta says the atmosphere is also reported to be tense in Dera Bugti, which adjoins Kohlu and is a major gas producing area in Pakistan.
The town of Sui, which houses major oil and gas installations, has been sealed off.
Paramilitary forces have set up roadblocks between Sui and Dera Bugti.
The head of Pakistan's Frontier Corps and his deputy were wounded after shots were fired at their helicopter in Balochistan province last week.
They had been inspecting an area where separatists had earlier fired rockets during a visit by President Musharraf.