Pakistan: Pakistan on Tuesday released 11 Iranians detained near the countries' border amid tensions over a deadly suicide attack in Iran that Tehran alleges has links to Pakistani intelligence officials, police said.

Authorities had first said the 11 were members of Iran's elite Revolutionary Guards, but then reversed course and identified them only as security officers. They were arrested Monday after shooting out the tires of a car carrying smugglers, Pakistan authorities said.

The arrests threatened to add to the strain between the two nations triggered by the Oct. 18 attack on the Iranian side of the border. They came a day after the Pakistani president met Iran's interior minister and vowed to track down the perpetrators of the blast.

Police official Dadur Rehman said the paramilitary Frontier Corps released the Iranians after an investigation.

"I do not have any idea why they were released," Rehman added in a phone call with The Associated Press from the area where the Iranians were held. He said he had not been privy to the interrogation.

Pakistan has been accused of supporting militant activities in two other neighboring countries, Afghanistan and India, greatly complicating relations with both of them. Strains in its relationship with another regional power would only add to Pakistan's problems as it battles al-Qaida and the Taliban within its borders.

One Pakistani official said three senior officers among the detainees probably belonged to Iran's powerful Revolutionary Guard.

Iran's Press TV carried what it described as a statement from the guard condemning the arrests, but saying that the 11 were not its members. The report cited "informed" sources as saying the arrested men were "border guards hunting fuel smugglers (who) accidentally entered Pakistan."

In an attempt to boost security in the region, Iran put the Revolutionary Guard directly in control of Sistan-Baluchistan province in April. Its officers typically take the lead in any operations on Iran's border.

The 11 officers were taken into custody in Mashkel district, about seven kilometers (four miles) from the countries' border in the southwestern Pakistani province of Baluchistan, paramilitary official Mohammad Naseer Baluch said.

He said they were arrested soon after they shot out the tires of a car driven by "two petty smugglers."

The Oct. 18 suicide attack killed 15 members of the Revolutionary Guard, including five senior commanders, and at least 27 others in the town of Pishin. Iranian officials blamed a Sunni rebel group known as Jundallah, or Soldiers of God, in the attack.

Iran's president and the guard chief have since publicly accused Pakistan's intelligence service of supporting Jundallah. Last week Iran's police chief Gen. Esmaeil Ahmadi Moghadam accused Pakistan of "having a direct responsibility" for the attack.

Pakistan President Asif Ali Zardari met with Iran's interior minister in Islamabad on Sunday to discuss the attack.

Afterward, he vowed to cooperate in capturing any attackers and said those behind the blasts "were the enemies of both countries."

Pakistani officials Monday said the arrested Iranians were in two cars and had no travel documents.

Pakistan and Iran have had generally good relations in recent years and in May the two countries signed a landmark pact for a natural gas pipeline into Pakistan.

Jundallah has waged a low-level insurgency in Iran's southeast in recent years, claiming to fight on behalf of the Baluchi ethnic minority, which it says is persecuted by Iran's government. Iran has also accused the United States and Britain of having links with Jundallah, charges both nations deny.

Iran's 120,000-member Revolutionary Guard is its strongest military force and is directly linked to the ruling clerics. It also controls Iran's missile program and guards its nuclear facilities.