An airstrike carried out by US assassination drones has killed five people and injured several others in Pakistan’s North Waziristan tribal area, on the border with Afghanistan.

US drones fired four missiles at two vehicles in the Shawal district of North Waziristan in the early hours of Sunday morning, killing five people, Press TV quoted the Pakistani television network Dawn News as saying.

It was the second drone attack in less than 24 hours in the Shawal district. On Saturday, US drones targeted a private compound in Shuwedar village in Shawal district, killing six people.

A Pakistani security official told media outlets on condition of anonymity that there were up to five drones hovering in the area at the time of the attack.

It was the fourth drone attack since the start of the Muslim fasting month of holy Ramadan and the second since Pakistan's intelligence chief, Lieutenant General Zaheer ul-Islam, visited Washington earlier this month.

Pakistan repeatedly declared that attacks by unmanned American aircraft violate its sovereignty and fan anti-US sentiment.

There has been a dramatic increase in US drone strikes in Pakistan since May, when a NATO summit in Chicago could not strike a deal to end a six-month blockade on convoys transporting supplies to occupation forces in Afghanistan.

On July 3 however, Islamabad agreed to end the blockade after the United States apologized for the deaths of 24 Pakistani soldiers in botched air strikes last November.

Pakistanis have held many demonstrations to condemn the United States’ violations of their national sovereignty.