Lebanese security forces have raided a prison after an investigation found detainees were connected to a suicide attack over the weekend, officials say.

Television pictures showed troops entering and searching inmates' rooms and smoke rising from Roumieh prison.

Officials said some detainees had set light to mattresses in protest at being transferred from one wing to another.

The interior minister said intercepted telephone calls proved some were linked to bombings in Tripoli on Saturday.

Al-Nusra Front, al-Qaeda's affiliate in Syria, claimed it was behind the attack on a cafe in the northern Lebanese city's predominantly Alawite district of Jabal Mohsen, which left nine people dead.

But officials said its rival, Islamic State, might have been responsible.
IS 'operations room'

Helicopters hovered above Roumieh prison as Internal Security Forces (ISF) personnel and ambulances entered the facility on Monday morning.

The official National News Agency quoted an ISF statement as saying it had carried out an operation to transfer a number of prisoners from "Building B" to "Building D".

Building D reportedly houses a number of high-profile Islamist militants.

"Some detainees started fires in protest against the security measures," the statement added. "However, the security situation is under control and no injuries have occurred."

Earlier, Interior Minister Nohad Machnouk told the Reuters news agency that the operation was launched after intelligence showed some of the inmates were connected to Saturday's attack.

"We made sure of their involvement... through monitoring their communications," he said.

Mr Machnouk said the prisoners had used mobile phones and internet video chat programme Skype to communicate with fellow militants.

"I can confirm that Roumieh prison is an operations room for Da'ish," he added, using a pejorative term for Islamic State based on an acronym formed from the letters of its name in Arabic.

Al-Nusra Front, several of whose members are inmates, threatened to retaliate for the raid.

"As a result of the deterioration of security in Lebanon, you will hear about surprises regarding the fate of the prisoners with us," the group said on its Twitter account.

Al-Nusra and IS are holding more than 20 Lebanese soldiers and police officers hostage. They were seized in an assault on the border town of Arsal in August. Four of them have already been killed.

BBC