Karachi, Pakistan ? In a foiled suicide bomb plot, Islamic militants planned to ram an explosives-laden Volkswagen into a car carrying U.S. diplomats in Karachi, Pakistan police said Sunday.

Police said they arrested three men Friday and Saturday and seized 250 sacks of ammonium nitrate, a fertilizer used in explosives. They said the suspects were trained at a camp in Afghanistan run by Islamic militants fighting Indian rule in the disputed province of Kashmir.

“They were preparing for the attack on American diplomats in the coming days, and they had the car bomb ready,” provincial police chief Kamal Shah told a news conference.

“They were surveying for appropriate place” on one of the main roads in this southern port city, frequently used by diplomats, he said.

Shah said one of the suspects, Asif Zaheer, was linked to a May suicide bombing outside a hotel in Karachi that killed 14 people, including 11 French engineers. “Asif Zaheer is an expert in explosives, and he was the man who prepared the car for suicide bombing at the Sheraton Hotel,” Shah said.

The plan apparently involved loading the nose of the rear-engine Volkswagen bug with explosives, waiting for a diplomatic vehicle to pass and ramming it to detonate the bomb.