US drone attacks are being stepped up along the Afghanistan-Pakistan border
At least 24 suspected militants have been killed in two separate attacks in Pakistan's North Waziristan tribal region, officials say.
A series of missiles is reported to have hit a vehicle and an alleged militant hideout in the Dattakhel area.
Officials say 12 militants were also wounded in the attack some 40km (25 miles) from the town of Miranshah.
A second barrage of missiles was fired on a militant camp immediately on the border with Afghanistan hours later.
There was no word on the identity of any of the militants killed, but the attack was in an area where members of an Afghan Taliban faction led by a commander known as Gul Bahadur operate.
Foreign fighters linked to al-Qaeda are known to be in the area.
Nearly 70 drone strikes have killed more than 200 people in Waziristan since the start of 2010, officials say.
Most of these strikes have been in the Dattakhel area.
At least six unmanned drone aircraft, believed to be operated by the CIA, were in the air when the missile strikes took place early on Tuesday, a local official told the BBC.
In the first attack, they fired at least 11 missiles - two hit a vehicle, killing four, while nine landed on a compound located in a ravine, he said.
The targets were located in the Dog Madakhel area of Dattakhel.
Officials and witnesses say those killed and injured are insurgents affiliated to militant leader Gul Bahadur.
Residents said drones had been hovering over the area overnight and were still in the air on Tuesday.
They said the militants had cordoned off the area and moved the injured to an unknown location.
Hours later, another pair of missiles hit a compound in the Gorwek area of North Waziristan killing another 10 suspected insurgents, officials say.
Some days ago, a drone strike on a compound in the same area killed five people and injured four.
The US has stepped up pressure on Pakistan's government since linking a failed car bombing in New York to the Pakistani Taliban.
Drone attacks have focused on North and South Waziristan, where US officials believe many al-Qaeda and Taliban fighters find shelter.
Pakistan publicly criticises drone attacks, saying they fuel support for militants. But observers say the authorities privately condone the strikes.
It is not known how many civilians have also been killed.
The American military does not routinely confirm drone operations, but analysts say the US is the only force capable of deploying such aircraft in the region.