Yemeni officials want more U.S. counterterrorism aid, including drone strikes and more U.S. military trainers and advisers, to fight a growing threat from Al Qaeda, Yemeni officials said late Wednesday.

But Yemen rejected a CIA and U.S. military request to expand the use of drone strikes to target groups of fighters who appear to be militants, the officials said.

Currently, U.S. counterterrorism forces are limited to striking clearly identified individuals with known links to Al Qaeda. Yemen approves each strike, Yemeni and U.S. officials say.

All officials spoke on condition of anonymity to discuss sensitive strategic matters.

U.S. officials say the CIA and U.S. military had asked the White House for permission to target larger groups if intelligence points to Al Qaeda-related activity. Such hits are known as "signature strikes," used by the CIA in Pakistan's tribal regions. Officials reached Wednesday night said the White House had not yet informed them of their decision. White House officials could not be reached for comment.

The request by the combined forces of the U.S. counterterrorism community to use signature strikes was driven by concerns that Yemen's Al Qaeda branch is building a safe haven in the south of the country that is proving impenetrable to Yemeni armed forces. The more secure Al Qaeda becomes, the more likely the group is to focus once again on attacking the U.S., officials say.

Al Qaeda in the Arabian Peninsula, as the Yemeni branch is known, is also becoming a top draw for foreign fighters, who used to travel to Afghanistan or Pakistan. Special operations raids in Afghanistan and CIA drone strikes in the Pakistan's tribal regions have made them less hospitable destinations, U.S. officials say, whereas Al Qaeda's Yemen branch is seen as gaining ground against a government that is allied with the Americans.

Yemen's new President Abed Rabbo Mansour Hadi is well aware his forces have lost ground against Al Qaeda, and has requested increased U.S. counterterrorist cooperation, seeking an influx of U.S. military trainers and advisers, the Yemeni officials said.

Hadi also gave the green light to expanded CIA drone activity, one of the officials said. "We are simply allowing the CIA to increase the pace of their strikes to match the U.S. military," he said.

But Hadi drew the line at signature strikes, fearing hitting larger groups with less precision than current strikes could serve to recruit more of the government's tribal enemies to Al Qaeda, the Yemeni officials said.