The Guards blamed "terrorist groups that are guided and supported by foreign forces" for the abductions and demanded action from Pakistan.

State news agency IRNA said 14 troops were seized, while local media and other sources gave the number as 11.

The force was "abducted between 4 am and 5 am in the Lulakdan area of the border by a terrorist group", IRNA said.

Lulakdan is a village 150 kilometres (90 miles) southeast of Zahedan, capital of Sistan-Baluchistan province which has seen a long-running separatist insurgency.

The abduction was carried out by "infiltrators linked to anti-revolutionary groups", the Guards said in a statement on their website.

They said operations were underway to find those responsible and called on Pakistan "to stamp out terrorists that are stationed near the border" and help recover the captive Iranians.

The unit was involved in "a security operation" and included two members of the elite Revolutionary Guards intelligence unit and seven Basij militiamen as well as regular border guards, said the Young Journalists' Club (YJC), a state-owned news website, in an article that was later deleted.

Pakistani security officials told AFP they had been informed of the abduction by Iran.

"We are in contact with local tribal people and are looking into it so that we can take timely action for their recovery," said a senior security official based in Quetta.

Sistan-Baluchistan has long been a flashpoint, with Pakistan-based Baluchi separatists and jihadists carrying out regular cross-border raids against Iranian security posts.

On September 28, the Guards said they had killed four militants who had slipped across the border.

The province has a large, mainly Sunni Muslim ethnic Baluchi community which straddles the border.

Sunni extremist group Jundallah (Soldiers of God) launched a bloody insurgency in the province in 2000 targeting the security forces and officials of Iran's Shiite-dominated government.

The campaign peaked with a spate of deadly attacks from 2007 -- including twin suicide bombings of a Shiite mosque that killed 28 people -- but abated after the group's leader was killed in mid-2010.

In 2012, Jundallah members formed a successor organisation called Jaish al-Adl (Army of Justice), which has carried out a spate of attacks on the security forces.

Iran has alleged that the group has received support from the US, Israel and Saudi Arabia, with the complicity of Pakistan.