American drones regularly target terrorists in the Federally Administered Tribal Areas (FATA) of Pakistan, President Barack Obama today said in a first such acknowledgment by the top US leadership on its highly successful but secretive programme.

"A lot of these strikes have been in the FATA, and going after al-Qaeda suspects who are up in very tough terrain along the border between Afghanistan and Pakistan," Obama said in response to a question during his first Google+ and You Tube live web chat from the White House.

"For us to be able to get them in another way would involve probably a lot more intrusive military action than the ones we're already engaging in," Obama said.

More than 130,000 questions were received, the White House said.

Obama said these strikes by unmanned drones are regularly carried out and these are "targeted focused effort at people who are on a list of active terrorists".

"For the most part, they've been very precise precision strikes against al-Qaeda and their affiliates, and we're very careful in terms of how it's been applied," he said, responding to the question.

This is for the first time that the US has publicly acknowledged the drone attacks inside Pakistan. The United States so far had refrained from publicly speaking on this issue.

According to the US media, 64 US missile strikes were reported in the area in 2011, down from 101 in 2010. The US drone attacks have been increased during Obama's presidency.

Obama claimed that drones have not caused huge number of civilians casualties.

"I want to make sure that people understand, actually drones have not caused huge number of civilians casualties... This is a targeted focused effort at people who are on a list of active terrorists," he said.

On Pakistan's cooperation in war on terror, Obama said: "I do agree that a country like Pakistan is one where our relations have got more strained because there are a lot of extremists inside their country and either for lack of capacity or political will they haven't taken them all on."

"In some cases, they have been very cooperative, in some cases not as much as we want," he added.