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.

Pakistan's foreign ministry said the two countries were coordinating efforts to "ascertain the whereabouts of the Iranian guards".

"No effort will be spared to assist our Iranian brothers in finding the Iranian guards," it said in a statement.

The Iranians were "abducted between 4:00 am and 5:00 am in the Lulakdan area of the border by a terrorist group", according to IRNA.

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 Revolutionary Guards, in a statement on their website, said operations were underway to find those responsible and called on Pakistan "to stamp out terrorists that are stationed near the border".

The group kidnapped 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.

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