The US will continue to use drone strikes in Pakistan, despite the “serious concerns” of Islamabad, Defence Secretary Leon Panetta said today.

The Pentagon Chief said the attacks were about “defending ourselves” and Pakistanis who, he said, were also the victims of terrorism

Speaking on the third day of his Asia trip from India, Mr Panetta said: “We have made it very clear that we are going to continue to defend ourselves. This is about our sovereignty as well.”

The US and India, he added, were trying to engage Pakistan to ensure a peaceful and prosperous South East Asia.

“Pakistan is a complicated relationship, complicated for both of our countries, but it is one that we must continue to work to improve.”

There have been eight US drone strikes in the last two weeks – before this increase, there had only been 11 such attacks in the preceding six months. A missile strike early on Monday is reported to have killed al-Qaeda leader Abu Yahya al-Libi in Hesokhel, a village to the east of Miranshah, the main town of the North Waziristan tribal area.

At least 14 people are thought to have been killed alongside him.

In a statement Pakistan said it had summoned the US deputy ambassador, Richard Hoagland on Tuesday and officially informed him that the strikes were”unlawful, against international law and a violation of Pakistan’s sovereignty.”

Adding: “The parliament (Pakistani) had emphatically stated that they were unacceptable. Drone strikes represented a clear red line for Pakistan.”