Secretary of State John F. Kerry promised new ideas to stop the escalating civil war in Syria, hinting Monday at a fresh international strategy to push Syrian President Bashar al-Assad toward the exit.

Making his inaugural overseas trip as secretary of state, Kerry appealed directly to the divided Syrian opposition to not lose heart.

“The Syrian opposition is not going to be dangling in the wind,” Kerry said in London, the first stop on a 10-day foreign tour that is expected to be dominated by discussion of the situation in Syria.

The dominant forum for those discussions is a meeting Thursday in Rome with international powers. The main U.S.-backed Syrian opposition group had threatened to boycott the planned strategy meeting over what it sees as continued U.S. and European fence-sitting, but the leader of the Syrian Opposition Coalition said Monday that his representatives would attend.

“After discussing with coalition leaders and making various calls . . . the coalition leadership have decided to stop the suspension of the visit to the Friends of Syria conference in Rome,” Mouaz al-Khatib wrote on his Facebook page.

Khatib made the announcement shortly after receiving a phone call from Kerry, who made an unusual personal entreaty.

Two years into a civil war that has killed about 70,000 people, Assad retains the loyalty of much of the military and has shown no willingness to broker an end to the fighting or accept asylum abroad.

Violence, meantime, has been closing in on central Damascus, as rebels make a new push to oust the regime from its seat of power. On Monday, a huge explosion ripped through the capital. It was followed by reports of widespread gunfire and shelling.

Syrian state television said the blast was caused by a car packed with explosives driven by a suicide bomber at the entrance to the northeastern Qaboun district, a rebel-held area that has been pounded by warplanes in recent days.

The threatened boycott of the meeting in Rome highlighted international inaction but also gave the opposition time to settle internal divisions. Khatib had earlier opened deep rifts within the group by offering talks without the precondition that Assad first step down.

“We are clear that there should be no negotiations with the Assad regime if Assad is not removed,” Fahad al-Masri, a spokesman for the Free Syrian Army’s joint command, said Monday. “Until then, we will fight.”

Earlier Monday, Syria’s foreign minister said the Assad government was willing to meet with rebels, the first time that a high-ranking official has indicated a desire for such talks.

But the offer was immediately dismissed as disingenuous by representatives of the Free Syrian Army and other opposition leaders.

Foreign Minister Walid al-Moualem’s comments came during a visit to Moscow, where Russian Foreign Minister Sergei Lavrov also appealed for negotiations.

“We’re ready for a dialogue with anyone who’s willing for it,” Moualem said, “even with those who carry arms. We are confident that reforms will come about, not with the help of bloodshed but through dialogue.”

Few in the opposition or international community were convinced that Assad has any genuine willingness to negotiate. Khaled Saleh, a spokesman for the U.S.-backed Syrian Opposition Coalition, dismissed the “empty offer.”

“Moualem’s offer is deceitful, and it seems that he wants to divide up those who are fighting against Assad,” Saleh said.

The embarrassing scramble to persuade the opposition to attend the Rome meeting also exposed a rare split between the United States and Britain. British Foreign Secretary William Hague made a point of noting that a political settlement is “blocked off,” because Assad refuses to step aside, and that the war is intensifying.

“That’s why in the United Kingdom, we believe we must significantly increase our support for the Syrian opposition,” beyond humanitarian aid, Hague said. “Our policy cannot stay static as the weeks go by.”

The European Union last week extended its ban on arms sales to Syria, a prohibition originally aimed at Assad that also forbids weapons export to rebels trying to unseat him.

Britain had argued to lift the ban and is moving to better equip moderate rebel forces within E.U. rules. The E.U. may reconsider the ban later this year.

The Obama administration has argued that weapons supplied to rebels could easily fall into the wrong hands. The United States and NATO also have ruled out direct military intervention. But Kerry suggested there are other ways to strengthen the rebels’ hand and perhaps force Assad to bargain.

“We are coming to Rome to make a decision about next steps and perhaps even other options that may or may not be discussed further after that,” Kerry said.

Morris reported from Beirut.