Five Iranian border guards reportedly seized and held captive in Pakistan for three weeks have been freed, an Iranian military official has been quoted as saying, although Pakistani authorities said they had no knowledge of the incident.

Iran's state-run Fars news agency on Saturday quoted General Massoud Jazaerisemi as saying: "Five Iranian troops who had been kidnapped on our eastern borders and transferred to Pakistan were freed."

He did not elaborate on the circumstances of the release, only saying that "the country's entire police and security apparatus were involved in this matter".

However, Pakistani authorities appeared to have no knowledge of the operation.

The government-run paramilitary Frontier Corps, which has primary responsibility for security in Baluchestan, said they had freed three Africans kidnapped by drug traffickers but had not recovered the Iranians.

A security official and the foreign office said on Sunday they were unaware of the incident.

Iran's official news agency IRNA said the Iranians, abducted by Sunni Muslim fighters on February 6 in the restive Sistan-Baluchistan province, were among 11 foreign hostages freed in an operation by Pakistani forces.

The impoverished and relatively lawless Sistan-Baluchestan province has been a hotbed of rebellion by a disgruntled Sunni minority in predominantly Shia Iran.

Angry over a spate of cross-border attacks by the so-called Jaish al-Adl (Army of Justice), Iran warned two weeks ago that it might pursue the rebels into Pakistani territory, provoking an angry warning from Islamabad.

Iran accuses both Pakistan and Saudi Arabia of supporting an armed Sunni rebellion.

Pakistan Prime Minister Nawaz Sharif enjoys warm relations with Saudi Arabia, which sheltered him after an earlier military coup forced him into exile. Sharif's cash-strapped government is also hoping for financial aid from the Saudis.

Saudi Arabia and Iran are rivals for influence in the Muslim world.