Syrian citizens, with their belongings loaded on trucks, flee from Yabroud in Syria's mountainous Qalamoun region toward the Lebanese-Syrian border town of Arssal on Feb. 12. (Hussein Malla/AP)

Syrian government warplanes pounded rebel-held areas near the border with Lebanon on Wednesday, contributing to what the opposition claimed were record levels of violence as peace talks founder.

New streams of refugees were forced across the border into Lebanon as U.N. special envoy Lakhdar Brahimi tried to find common ground between the warring sides during their second round of negotiations in Geneva. The United Nations said Wednesday that it would bring forward a trilateral meeting with Russia and the United States, which it is hoped will kick-start deadlocked discussions.

Since the peace talks began nearly three weeks ago, violence has continued unabated, with civilians killed at a record rate, according to the Britain-based Syrian Observatory for Human Rights. Barrels packed with explosives rained down on the city of Aleppo again Wednesday, while in the mountainous Lebanese border region of Qalamoun, airstrikes battered several towns.

Wafic Khalaf, a member of the municipal council in the Lebanese border town of Arsal, said the dirt roads across the border were “like a highway” Wednesday as more than 500 families — about 2,500 people — fled.

Amid the violence, Brahimi has expressed exasperation over the “laborious” pace of talks, while the United States has admitted that diplomacy is failing.

While a humanitarian deal to evacuate civilians from besieged areas of Homs and allow some aid deliveries had provided hope for progress, the two sides have not been able to agree on an agenda.

The opposition wants to discuss a political transition, while the government insists that talks focus first on combating terrorism in the country. Damascus has rejected Brahimi’s suggestion that the two issues should be discussed in parallel.

In its “statement of basic principles,” it called for the establishment of a transitional governing body, with full executive powers, which would be the only legal representative of the Syrian people until elections could be held. It also said that the body would work to ensure the withdrawal of foreign fighters from the country and end violence. The statement avoided mention of President Bashar al-Assad.

As pressure built Wednesday, a meeting between Brahimi and two officials from the United States and Russia — Undersecretary of State for Political Affairs Wendy Sherman and Deputy Foreign Minister Gennady Gatilov — was brought forward a day and now is scheduled for Thursday.