LAHORE/PESHAWAR (REUTERS) - Dozens of gunmen from criminal gangs kidnapped seven Pakistani police from a checkpoint in the normally peaceful province of Punjab on Sunday, officials said.

The kidnapping, and further fighting between insurgents and the military in the northwest of the country, underscored the range of security problems facing Prime Minister Nawaz Sharif.

Pakistan, a nuclear-armed nation of 180 million, is beset by a Taliban Islamist insurgency in the northwest and a separatist insurgency in the west. Murders, kidnappings and extortion by criminal gangs are common. Sectarian violence is growing.

Sunday's attack, by gunmen from different gangs, targeted a police checkpoint in Obaro, inside Punjab but at the intersection of three provinces, said District Police Officer Sohail Chatha.

"We have launched a rescue operation," he said.

A statement from Sharif's office said he took "serious notice" of the kidnapping.

Police are poorly trained, paid and equipped. Rather than instituting reforms, Sharif's government has handed much of the responsibility for security to the powerful military, which has a history of mounting coups and is frequently accused of extrajudicial killings.

In separate developments, the military said air strikes killed 44 insurgents on Saturday in Khyber and North Waziristan, two remote, mountainous northwestern areas bordering Afghanistan.

The military said five soldiers and 27 militants were killed in fighting in Khyber on Thursday. Access to the areas is restricted and it is difficult to independently verify casualty figures.

Tirah Valley in Khyber is a key smuggling corridor into Afghanistan where militants have many small bases. North Waziristan was the Taliban's last major stronghold until the military launched an offensive there last June.

Residents and officials confirmed at least nine deaths from the bombing in Tirah and seven in North Waziristan. "Two fighter jets started bombing in Tirah valley on Saturday morning for two hours," said 58-year old tribal elder Sakhi Jan.

He said his family fled but his younger brother remained to stop militants from occupying the house. The brother said residents saw militants bring out nine bodies and 13 injured militants. A local government official quoting tribal elders said around a dozen people were killed in Tirah valley.

In North Waziristan, Pakistani air strikes killed seven militants in two locations, a resident said. "Local, Punjabi, Afghan and foreign militants are living here," he said. "Sometimes the war planes target their positions but militants have become very clever and don't get together in large numbers."

A security official in Mir Ali, North Waziristan, said around a dozen militants had been killed.