BEIRUT: Roads leading to the country’s largest prison were blocked Tuesday night in light of information about a possible attack by Islamist groups to secure the release of scores of supporters.

The Internal Security Forces said police would temporarily prevent the passage of all motor vehicles – including trucks, tanks, pickups, cars and motorbikes – on both lanes leading to the prison. Traffic will be redirected via the Metn Highway and other routes.

The statement cited “security reasons” for the heavy measures, which went into effect at 7 p.m.

Speaking to The Daily Star, sources said security services had received serious information on possible attacks targeting the prison.

In one of the scenarios being prepared for, several suicide bombers would allegedly blow up the gates of the prison, while other attackers would take advantage of the resulting commotion and panic to free certain inmates.

Roumieh holds dozens of Islamist detainees who have been awaiting trial for years, with the majority linked to the 2007 Fatah al-Islam clashes with the Lebanese Army in the Palestinian Nahr al-Bared refugee camp in north Lebanon.

The prisoners have previously protested the crowded rooms and slow trial procedures.

Last month, the Islamic State of Iraq and Greater Syria (ISIS) dedicated a song to Roumieh’s Islamist inmates, calling for their release and expressing their hope that the entire prison would be brought down.

ISIS set the holy month of Ramadan as the deadline for the release of the relevant inmates, saying it would otherwise use its own means to free them, the source said.

Meanwhile, Lebanese officials reassured citizens that the overall situation in the country was stable.

“There is no favorable environment for terrorism in Lebanon. We are united on the domestic level and the security situation is under control, which prevents the emergence of such environments,” Prime Minister Tammam Salam said during an interview with Al-Jazeera.

Interior Minister Nouhad Machnouk also insisted security was under control despite recent bombings.

“I reassure [the Lebanese] that security agencies are alert and coordinate with each other at the highest level,” Machnouk told reporters at the Interior Ministry.

Asked whether he feared Lebanon would plunge into an Iraq-style sectarian conflict, Machnouk said: “Never. Lebanon’s circumstances and makeup are different. Lebanon does not resemble Iraq at all.”

Three suicide bombings rocked Lebanon late last month, renewing fears in a country that was hit with a series of attacks late last year and earlier this year linked to the Syrian war.

The last bombing occurred last week at the Duroy hotel in Beirut, where a Saudi suicide bomber blew himself up in his room to avoid arrest during a raid by General Security. A second Saudi in the room who survived was arrested and confessed to being part of a double suicide-bomb plot against a restaurant in Beirut’s southern suburbs frequented by Hezbollah officials. He also told investigators ISIS had recruited him for the attack.

A Saudi delegation arrived in Beirut Monday to follow up on his case, but a source close to Machnouk told The Daily Star that it would not be involved in investigation.

“The Cabinet condemns the terrorist bombings in the ... Lebanese capital,” said a statement by Saudi Culture and Information Minister Abdulaziz bin Mohieddin Khoja, “and praises the efforts of the two governments in pursuing the terrorist cells and the success they have achieved in this concern.”

Earlier, Machnouk chaired the regular meeting of the Central Security Council, which was attended by heads of security services.

Attendees discussed efforts to pursue terror networks across the country and the ongoing implementation of the security plan in Bekaa Valley and the north. Its decisions were not publically announced.

The Army has this week increased security measures at checkpoints in the northern Bekaa, the National News Agency reported.

The NNA said the military arrested 20 Syrians over the past three days after they illegally entered Lebanon, and also confiscated a “suspicious” car.

The Future bloc of former Prime Minister Saad Hariri praised the security services’ efforts, which have led to a number of terror plots being thwarted, and called on authorities to continue the strict security measures.

But in a statement after its weekly meeting, the bloc added that confronting terrorism could not take place through security measures alone, and reiterated its calls for Hezbollah to pull out from Syria.

“Today, before tomorrow, Hezbollah should withdraw from Syria and stop implicating Lebanon and the Lebanese [in Syria’s conflict] and exposing their security and future to dangers, along with ruining their economy,” the statement said.

Meanwhile, the Al-Qaeda-linked Abdullah Azzam Brigades vowed to carry out further attacks against Hezbollah and its allies in Lebanon until the party withdrew from Syria.

“When we bombed the embassy of its patron, Iran, and then the center of cultural crime [The Iranian Cultural Center] for the sake of the oppressed in Syria and Lebanon and in response to the aggression, they shouted: Terrorists!” tweeted the group’s spokesperson Sheikh Serajeddine Zoraiqat. “If terrorism is the response to your crimes, then wait for a series of terrorist attacks that will have you forget previous ones until safety is restored in Syria.”

The Brigades have claimed responsibility for the bombing outside the Iranian Embassy in Beirut last year and this year’s attack against the Iranian Cultural Center. Iran is a major backer of Hezbollah.

Meanwhile, a roadside bomb exploded early Tuesday close to a Lebanese Army patrol in Tripoli. There were no casualties from the 3:15 a.m. blast, the Army said.

In a statement, the military said the 800-gram bomb – enclosed in a box with metal balls – was planted on the side of a road in the neighborhood of Bab al-Raml. The military police have launched an investigation.