British Foreign Secretary William Hague called Sunday for a strong response to the use of chemical weapons in Syria, saying the issue went wider than the conflict in the Middle Eastern country.

Hague said that although the British parliament had rejected joining military action against Syria, he backed anticipated U.S.-led air strikes to stop President Bashar Assad's regime using poison gas again.

U.S.-led military strikes on Syria would boost all of the country's opposition forces, including jihadists, but would not be enough to precipitate the fall of Bashar Assad's regime, analysts say.

U.S. President Barack Obama is seeking congressional authorization for limited military strikes on Syria in response to an alleged chemical weapons attack in the suburbs of Damascus on August 21.

The Pentagon is readying more intense and longer attacks on Syria than originally planned, set to last three days, the Los Angeles Times reported Sunday.

War planners now aim to unleash a heavy barrage of missile strikes to be followed swiftly by additional attacks on targets that may have been missed or remain standing after the initial launch, the Times cited officials as saying.

Syrian rebels, including jihadists linked to Al-Qaida, have taken control of the historic Christian town of Maalula, north of Damascus, a watchdog and a resident said on Sunday.

Maalula is home to around 5,000 residents and is of strategic importance for the rebels, who are trying to tighten their grip around the capital Damascus, adding a northern post to existing bases in the south and west of the city.

Thousands of Tunisians took to the streets of Bardo, near the capital Tunis, late Saturday, calling for the government led by the moderate Islamist Ennahda party to step down.

They were marking the end of a 40-day period of mourning after the assassination of opposition leader Mohamed Brahmi, shot dead outside his home on July 25.

A U.S. congressional panel posted videos of Syrian victims Saturday, many of them children, as the White House presses its case for a strike against Damascus.

The 13 graphic videos were shown to members of the Senate Intelligence Committee on Thursday, according to the panel's website, which says they "explicitly claim to show victims of a chemical or poison gas attack."

More than 1,000 Christians held a prayer vigil for peace in Damascus on Saturday, heeding a call from the Vatican, as the U.S. pressed for a military strike on Syria.

Men, women and children thronged Our Lady of Dormition, the Melkite Greek Catholic patriarchal cathedral in the Old City of Damascus, for an emotionally charged plea for peace.

Pope Francis called for reconciliation and dialogue in Syria on Saturday as he led a mass vigil for peace in the war-torn country.

"In beloved Syria, in the Middle East, in all the world, let us pray for reconciliation and peace, let us work for reconciliation and peace," the pope said.

Sweden and Poland warned against knee-jerk reactions to the crisis in Syria on Saturday, saying that any international effort to solve it will require a commitment "for decades to come".

Speaking at a regional NATO conference in the Latvian capital, Riga, Swedish Foreign Minister Carl Bildt said the West was being short-sighted regarding the instability sweeping the Middle East.

The United States and France said Saturday that international backing was growing for military strikes to punish the Syrian regime for alleged chemical attacks, after European Union nations called for a "strong" response.

U.S. Secretary of State John Kerry said the number of countries ready to take military action was now in the "double digits", after earlier attending a meeting where EU foreign ministers united to call for action against Syrian President Bashar Assad's regime.