Updated

U.S. missiles killed at least eight alleged militants Thursday in a tribal region along the Afghan border -- the third such drone attack since the U.S. killing of Usama bin Laden, Pakistani intelligence officials told Reuters.

Pakistani officials say the drone strikes targeted the North Waziristan region.

"At least four drones are still flying over the area," one official told Reuters.

The strike is evidence that the U.S. is not letting up on cross-border drone strikes into Pakistan despite Pakistani officials' complaints that the United States violated its sovereignty by killing bin Laden on their soil. Even before bin Laden's death, the drone attacks were a source of increasing tension in the now severely strained U.S.-Pakistan relationship.

In Abbottabad, a garrison town in northwest Pakistan where the May 2 raid by U.S. Navy SEALs killed the leader of the Al Qaeda terror network, about 300 members of former Prime Minister Nawaz Sharif's party rallied Thursday in the main bazaar, denouncing both the American government for approving the raid and Pakistani leaders.

In the aftermath of the raid on bin Laden, Pakistan's ruling party has defended the country's powerful army, allowing it to investigate its own intelligence fiasco in the case.

Sharif, the main opposition leader and former premier, on Wednesday called for the judiciary -- not the army -- to investigate the events surrounding bin Laden's death, but it's unclear if his proposal will gain any traction.

The demonstrators in Abbottabad, mostly from Sharif's Muslim League-N party, chanted: "Go, America, go!" The crowd carried a banner that read "American terrorism is not acceptable," and also shouted slogans of appreciation for bin Laden.

Murtaza Javed Abbasi, an activist, demanded accountability from Pakistan officials who claim they did not know that bin Laden was hiding in Abbottabad. He noted that the Pakistani people were footing the bill for a huge military budget.

"Why aren't they able to protect our sovereignty?" he asked. "The army chief should reply to this and those who are responsible should be hung."

Two Pakistani intelligence officials said Thursday's drone-fired missiles hit a vehicle in the Datta Khel area of North Waziristan, an Al Qaeda and Taliban stronghold that has been subject to frequent missile attacks. Militants often use the area to cross into Afghanistan where many are involved in fighting U.S., NATO and Afghan forces.

The two officials spoke on condition of anonymity because they were not authorized to speak to the media. The identities of those killed in the missile strike have not been confirmed.

The Associated Press contributed to this report.