BEIRUT - Rebel fighters battled regime troops inside the walls of the sprawling central prison compound in Syria's largest city Wednesday, hours after blowing open the gate with twin car bombs in an attempted jailbreak, activists said.

The orchestrated assault began at dawn, but by nightfall, the rebels had not dislodged regime forces or freed the 4,000 prisoners held there, according to two pro-opposition monitoring groups.

Across Syria, the Internet was restored after a blackout of more than eight hours, the second nationwide outage in a week. Syria's Communications Ministry blamed a rebel bombing, which it said cut a cable north of the capital of Damascus but gave no details. Earlier, the state news agency SANA had linked the outage to a technical problem.

At the United Nations, the General Assembly voted 107-12 with 59 abstentions to approve an Arab-backed resolution calling for a political transition in Syria and condemning President Bashar al-Assad's regime for "gross violations" of human rights.

Earlier this month, the United States and Russia agreed on a joint push to get Syria's political opposition and representatives of the Assad regime to negotiate a peaceful transition in Syria. An international conference, possibly to be held in early June, would help launch such talks.

However, both the opposition and the regime have said they want to hear more about the agenda, the venue and the participants before signing up. The two sides remain far apart on the terms for such negotiations, with the opposition insisting Assad must step down first and the regime unwilling to commit to an open-ended cease-fire.

British Prime Minister David Cameron called for urgent action to pressure the Syrian government and opposition to put forward names for a transitional government that everyone can support so negotiations can get started.

"My concern is that we'll get into too long a process," he told reporters after meetings at the United Nations. "Urgent action needs to be taken right now to put pressure on the participants to get together . . . and that's what I'll be putting my efforts behind."