The Pakistani military's latest ground and aerial onslaught in the troubled northwest killed at least 34 Islamist militants Saturday while five of its troops also died during clashes, security officials said.

The attacks come days after Pakistan's powerful military chief General Raheel Sharif ordered his troops to begin the last phase of a bloody operation targeting militants in the country's restive northwest along the Afghan border.

Pakistani air force jets pounded militants' hideouts in the northwestern tribal belt, killing at least 15 Taliban insurgents including six Uzbeks.

The strikes were carried out in the Maizer area of the Datta Khail region in North Waziristan, which is considered a stronghold for Tehreek-i-Taliban Pakistan (TTP) militants.

"As many as four hideouts were destroyed in the strikes this morning. Among the 15 killed militants were six Uzbeks," a security official in the area told AFP.

Later in the evening, the military issued a statement saying its "ground forces surrounded a group of fleeing terrorists in the Mangroti area near the Afghanistan border in the Shawal region of the North Waziristan district and 19 militants were killed during the intense exchange of fire".

"Four security forces personnel including an officer also embraced martyrdom," the statement added.  

A senior security official in Peshawar confirmed the strikes and clashes.

"The air strikes have increased in the last few days and we have hit targets today also. We have hit the hideouts many times during the last few days," the official, who spoke on the condition of anonymity, told AFP.

Also on Saturday, a Pakistani soldier was killed and two others wounded when their vehicle hit an improvised explosive device planted on a roadside in North Waziristan's Datta Khail. 

The Pakistani army launched Operation Zar-e-Azb under US pressure in 2014 in a bid to wipe out militant bases in the North Waziristan tribal area and bring an end to the near decade-long Islamist insurgency that has cost Pakistan thousands of lives. 

The conflict zone is remote and off-limits to journalists, making it difficult to verify the army's claims, including the number and identity of those killed.

Pakistan's Islamist insurgency began after the US-led invasion of neighbouring Afghanistan in 2001 which led to a spillover of militants across the border and a surge in recruitment for Pakistani extremist groups. 

Pakistan's relative success in fighting militancy stands in marked contrast to Afghanistan, which is facing record numbers of civilian casualties following the withdrawal of NATO combat troops at the end of 2014.