Tens of thousands gathered in one of the biggest-ever protests in the Pakistani city of Lahore Sunday, December 18, to condemn NATO and United States over the killing of 24 soldiers along the Afghan border.

The protestors, mainly from Islamist groups and political parties, vowed they would march to the capital Islamabad if the government did not cancel agreements between the U.S. designed to fight terrorism.

"We will hold a march towards the capital if the government does not revoke agreements of cooperation in the war against terror with the U.S.," said Hafiz Muhammad Saeed, a senior leader of the Pakistan Defense Council (PDC).

About 3,000 activists from the Council, which organized the rally, also acted as guards in addition to a 1,000-strong police contingent.

Saeed, who heads the charity Jamaat-ud-Dawa and founded the Lashkar-e-Taiba (LeT) faction blamed by India and the U.S. for the 2008 attacks in Mumbai, warned that "we will no longer tolerate any attacks on our soil."

"The U.S. should not turn its missions in Pakistan into spying stations," he said, adding that "we will respect Americans if they live in Pakistan as guests but any other agenda will not be tolerated."

Saeed called on Pakistan's government to decide on a date that would see it take the country "out of the war against terror" and vowed "every sacrifice to preserve and uphold sovereignty and territorial integrity of the country."

Since the attacks last month, Pakistan has charged that U.S.-led forces deliberately carried out the air strikes that killed the two dozen soldiers, but the U.S. has insisted the November 26 incident was a regrettable mistake.