TEHRAN (Reuters) - Iran has documents to prove the United States and Britain, the Islamic Republic’s two Western arch foes, back a group that killed 16 abducted Iranian police officers, state radio reported on Saturday.

Shi’ite-dominated Iran said this month the Sunni group Jundollah (God’s Soldiers) had killed 16 police hostages who were abducted from a checkpoint in the southeastern Sistan- Baluchestan province in June.

Tehran, which often accuses Britain and the United States of trying to destabilize the Islamic Republic, has said Jundollah’s head, Abdolmalek Rigi, is part of the Sunni Islamist al Qaeda network.

“There are documents that show that Britain and America are supporting Rigi’s terrorist group with arms and information,” the radio quoted Ebrahim Raisi, first deputy to Iran’s judiciary chief, as saying.

“The Iranian nation will avenge the blood of the border post soldiers powerfully,” it added, without providing further details on the documents.

Osama bin Laden’s al Qaeda is blamed for numerous attacks on the United States, including the September 2001 assaults on New York and Washington that killed some 3,000 people.

Jundollah operates mostly in Sistan-Baluchestan, a volatile region near the border with Pakistan, home to Iran’s mostly Sunni ethnic Baluchis. The area is notorious for clashes between security forces and heavily armed bandits and drug smugglers.

“All forces -- police, security and the judiciary branch -- are determined to deal very strongly with the soldiers of the devil,” Raisi said, referring to Jundollah.

Similar comments about action against the group’s attacks were made by Ahmad Khatami, a senior Iranian cleric, during a sermon to worshippers on Friday in Tehran.

Iran has blamed Jundollah for other abductions and in 2007 the group claimed responsibility for an attack on a bus carrying Iranian Revolutionary Guards that killed 11 people.

Iran has not had diplomatic ties with the United States since 1980. Britain has an embassy in Tehran but relations have often been strained over the years, mainly because of Britain’s involvement in Iranian politics when it was an imperial power.