LONDON (Reuters) - At least 10 Iranian security personnel including Revolutionary Guards were kidnapped on the border with Pakistan on Tuesday, Iran’s state media reported, and a separatist group said it had seized them as revenge for the oppression of Sunni Muslims.

The Revolutionary Guards, Iran’s top security force, said in a statement carried on state television that some of its members had been abducted by a militant group at a border post in the city of Mirjaveh in Sistan-Baluchestan province.

Iranian officials held talks with the Pakistani ambassador in Tehran and called on Islamabad to “use all possible means” to free them.

The Guards did not say how many were kidnapped, but state news agency IRNA quoted an unnamed official as saying 14 people had been kidnapped around 4 a.m. or 5 a.m.

The Guards said they believed the Iranian forces had been deceived by “insiders”, but did not elaborate. Fars news agency said there were reports Iranian forces had been poisoned by food before being captured and taken to Pakistan.

Ebrahim Azizi, spokesman for Jaish al-Adl, a Sunni militant group, said the group had seized more than 10 people.

“This morning Jaish al-Adl forces attacked a border post in Mirjaveh, and captured all their weapons,” Azizi said in an audio message sent to Reuters.

The group also claimed responsibility on its Twitter account.

Azizi said the attack was retaliation for what he called the Iranian state’s oppression of Sunnis in Sistan-Baluchestan, a mainly Sunni province with a long history of separatist unrest.

SAFE HAVENS?

Iran’s Shi’ite Muslim authorities say militant groups operate from safe havens in Pakistan.

Foreign ministry spokesman Bahram Qasemi was quoted as saying by Fars new agency the Pakistani ambassador had attended a meeting in the ministry. Iran asked Islamabad to “use all possible means, without any delay” to free those abducted.

The Revolutionary Guards said in a statement: “We expect Pakistan to confront these terrorist groups that are supported by some regional states, and immediately release the kidnapped Iranian forces.”

Pakistan’s foreign ministry said in a statement: “Both militaries, under a joint mechanism established since last year, are working to ascertain the whereabouts of Iranian guards.”

In previous cases of cross-border clashes, Iran threatened to hit militant bases in Pakistan unless Islamabad took action.

But this time Brigadier General Mohammad Pakpour, the head of the Guards’ ground forces, said Iran was ready to conduct “joint military operations with Pakistan” against the militant groups to release the kidnapped personnel.

Iran has accused Saudi Arabia of funding separatist groups on its territory. Riyadh has denied any involvement in Iranian internal affairs.

In September, the Revolutionary Guards killed four Sunni militants at a border crossing with Pakistan, including the second-in-command of Jaish al-Adl.

Jaish al-Adl kidnapped five Iranian border guards in 2014, releasing four of them two months later after mediation by local Sunni clerics.