Islamabad, Pakistan (CNN) -- Three suspected U.S. drone strikes in Pakistan's tribal region killed at least 21 suspected militants Friday, Pakistani intelligence officials said.
All three strikes occurred in the Khyber Agency, one of the seven districts of Pakistan's volatile tribal region bordering Afghanistan.
The attacks come as the strikes are expanding into new areas of Pakistan for the first time, and they may signal an extension of the hunt for terrorists along the border with Afghanistan.
Two Pakistani intelligence officials said the first attack was on a militant hideout in Sippah village, in the area of the Tirah valley, where seven people died. The second was on a militant hideout in the village of Nakai, where eight more were killed.
In the third strike, two missiles were fired on a militant training center in the village of Sangana in Tirah Valley, killing six suspected militants, the two intelligence officials said.
The strikes targeted a local militant group, Lashkar-e-Islam (Mangal Bagh group) in Khyber Agency, the officials said. Ali Marjan, an important local commander of Lashkar-e-Islam, was killed in the first strike.
The intelligence officials asked not to be named because they were not authorized to speak to the media.
U.S. officials normally do not comment on suspected drone strikes, but the United States is the only country known to have the ability to launch missiles in the region from remote-controlled aircraft.
In the past, the strikes have focused on North and South Waziristan, but the intelligence officials said many militant leaders have been pushed out of those areas by the drone activity, relocating to areas further north like Khyber.
On Thursday, a Pakistani Intelligence official confirmed the first drone strike in Khyber, where a suspected drone fired two missiles and killed 7 militants.
Based on a count by the CNN Islamabad bureau, Friday's strikes bring the total for the year to 106 this year, compared to 52 in all of 2009.
CNN's Nasir Habib and journalist Nasir Dawar contributed to this report.