PESHAWAR, Pakistan – Twin suicide bomb blasts that killed at least 80 paramilitary recruits in northwest Pakistan on Friday — an attack that Taliban militants said was meant to avenge the killing of Osama bin Laden by U.S. commandos — could trigger new doubts among Pakistanis about the value of Islamabad’s already rocky relationship with Washington.

The bombers targeted scores of Frontier Constabulary paramilitary recruits who had just completed six months of training and were boarding vans outside the center’s main gate before going on a 10-day leave, police and survivors said. The base is located in Shabqadar, a town near the edge of Mohmand, a tribal area where Pakistani troops have struggled for years to rein in Pakistani Taliban militants.

The attack was Pakistan’s deadliest this year, and the first major terror strike in the country since bin Laden’s killing.

Pakistanis have grown increasingly worried that they will bear the brunt of retaliatory attacks by militants angered by the May 2 killing of the al-Qaida leader by U.S. Navy SEALs at his compound in the military city of Abbottabad, which he used as sanctuary for five years. Washington’s decision to carry out the mission without Islamabad’s knowledge or authorization angered many in Pakistan who saw the effort as a gross violation of their country’s sovereignty.

Reacting to news of the blasts, Bashir Bilour, a senior minister for Khyber-Pakhtunkhwa province, questioned whether, despite the billions of dollars that Pakistan receives from Washington in economic and military aid, the country was paying too heavy a price for its role as an ally in the war on terror.

“I don’t care if someone is giving us money; we are not a purchasable commodity,” Bilour told reporters in Peshawar. “We cannot be bought. We can live in hunger, but we won’t compromise our national interests.”

The Pakistani Taliban claimed responsibility for the attack, explaining it was the first of a wave of planned strikes meant to avenge bin Laden’s killing, according to news agencies and Pakistani media. The Pakistani Taliban, the country’s homegrown insurgency, is closely allied with al-Qaida and is one of several militant groups that have provided the terrorist network sanctuary in the volatile tribal region along the Afghan border.

The bombers struck at a time when recruits appeared to be particularly vulnerable — just as they were leaving the training center in large groups.

As the recruits loaded their luggage onto the vans, a bomber on a motorcycle drove up and detonated his explosives near the main gate. Moments later, a second bomber on foot detonated a larger blast as onlookers rushed to help recruits wounded in the first explosion.

Most of the dead were recruits, police said. More than 100 people were injured.

“I was just four yards from the gate when the first blast threw me to the ground,” said recruit Ajsam Ali, 20, from his hospital bed in Peshawar, where he was recovering from wounds to his head, left arm and left foot. “The air was black with smoke and I couldn’t see. It was chaos. People were screaming. There were dead and maimed people lying all over the street.”

Tahir Ali, a Frontier Constabulary soldier assigned to the center, said 62 paramilitary troops were providing security as recruits boarded their vans about 6 a.m. However, the recruits were exposed to pedestrians and morning traffic moving past. More than 800 recruits were streaming out of the base, bags in hand.

Maroof Khan, a 20-year-old paramilitary recruit, said he was loading his baggage onto a van when the first blast knocked everyone to the ground.

“I was hit in my leg, but I managed to hobble to a nearby mosque,” he said. “Everyone was in a panic. Suddenly, there was a second, much larger explosion. I looked around and saw many of my friends dead on the ground.”

“This is so cruel, attacking young recruits like this,” Shafiq ur-Rehman, a 21-year-old recruit, said from his hospital bed, surrounded by a ward filled with recruits in bloodied tunics, some of the victims wailing in pain. “We’re just innocent kids. We’ve never harmed anyone. These are young boys that they’ve killed today.”