Karachi, Pakistan ? Police and intelligence officials said Wednesday that they had arrested an Islamic militant who organized the June 14 car bomb attack on the U.S. Consulate here and was plotting to assassinate Pakistan’s president this week.

Sharib Ahmad, 30, considered the most-wanted militant in Pakistan, was arrested late Tuesday in this port city with five other men, the officials said. Ahmad was identified as the leader of the attack on the consulate by three other suspects in the case.

Twelve Pakistanis, including six women, were killed in the bombing, which heavily damaged the fortified consulate. Karachi police said at the time that the bomb was hidden in a vehicle parked outside the 10-foot wall surrounding the building.

The six militants captured Tuesday were found at a house in the middle-class residential district of Dhoraji, less than a mile from the site of a military equipment exhibition that Gen. Pervez Musharraf, the Pakistani president, attended on Monday. The raid also netted a large cache of weapons, ammunition and explosives, including an anti-tank recoilless rifle.

“In their sole aim to kill President Musharraf these militants had collected 70 hand grenades, 40 rocket-propelled grenades and rockets and about (2,000 pounds) of bomb-making chemicals at their hide-out in Karachi,” said a ranking Karachi police official who asked not to be identified. He added: “This is the largest seizure of arms and ammunition from any terrorist group in Pakistan since 9-11.”

Maj. Gen. Rashid Qureshi, Musharraf’s spokesman, Wednesday night acknowledged the arrest of “several terrorists and seizure of weapons and ammunition,” but denied that the militants were plotting to kill the president.

Officials said all six of the men arrested Tuesday were associated with Harkat ul-Mujaheddin al-Almi, a radical Islamic splinter group that police said was also involved in an abortive bid to assassinate Musharraf here in April by placing a car loaded with explosives on a street where the presidential motorcade was to pass. Police said the plot failed only because of a faulty remote control device.

Officials say they believe Islamic militants in Pakistan, furious with Musharraf’s decision to side with the United States in its war against terrorism and its military campaign against the Taliban and al-Qaida in Afghanistan, are waging a terrorist campaign to destabilize his government. U.S. and other Western citizens also have been targets of the armed campaign.

Police raids last week resulted in the arrest of about a dozen foreign militants suspected to be members of al-Qaida, including Ramzi Binalshibh, reputed to be a principal planner of the Sept. 11 terrorist attacks in the United States.