Syria's insurgency appeared to make further territorial gains in the south, on Wednesday, antigovernment activists reported, saying that rebel fighters had seized a military base near the city of Dara'a, where the uprising against President Bashar al-Assad first began more than two years ago.
The Syrian Observatory for Human Rights, a group based in Britain that has a network of contacts inside Syria, said rebel groups had seized the air defense base of the 49th battalion near the town of Alma on the northern outskirts of Dara'a, near the Jordanian border. Last week, the rebels made advances in the nearby town of Dael, which sits on the Dara'a-Damascus highway.
Rebel fighters secured Dael after having overrun military checkpoints there, positioning them to control the highway and threaten a main conduit for the government to resupply forces in the Dara'a area. The highway is also a doorway to Jordan, an increasingly important point of entry for weapons for the insurgency.
The rebel advances in southern Syria in and around Dara'a, if not reversed by Mr. Assad's military, would add to the patchwork of territory held by the insurgency in the north near the Turkish border and in the east near the Iraq border, as well as portions of Aleppo, the northern Syrian city that was once its flourishing commercial capital. The government remains in firm control of most major cities, including Damascus, but it has become ever more difficult for the strained Syrian military to retake contested areas.
There was no indication that rebels were planning an imminent attempt to seize the city of Dara'a, where a handful of youths were were thrown in jail in March 2011 and brutalized for scrawling "the people want the regime to fall" and other anti-Assad graffiti on walls. That episode of repression during the height of the Arab Spring was the catalyst for an uprising that turned into a civil war.
The news from southern Syria came as civil war violence spilled across at least two other national boundaries.
Lebanon's national news agency and witnesses in the Bekaa Valley town of Ersal, a few miles from the Syrian border, said a Syrian military helicopter had fired at least two rockets that hit the edge of the town, close to a Lebanese Army checkpoint. No casualties were reported, but one resident said it was the first time he had seen such an attack. On Tuesday night, the Israeli military destroyed a Syrian post with tank fire after shots had been fired from the Syrian side at an Army jeep in the Israeli-held Golan Heights, Israeli military officials reported.
Antigovernment activists in Syria reported clashes elsewhere on Wednesday, including what they described as a rebel raid on a checkpoint at the Adra central prison in the Damascus suburbs and fighting outside the nearby Iben Sina hospital for mental and nervous disorders.
At least 70,000 people have died in Syria since the anti-Assad uprising began. The Syrian Observatory has calculated that more than 6,000 people died in March, the biggest monthly toll so far.
Mr. Assad's control of the Dara'a area is now believed to be in contention because of a more aggressive insurgency. One sign has been the pattern in refugee flows into Jordan. Some Syrians who had fled their homes in the Dara'a area want to go back, a trend that opposition activists are not discouraging.
Mohammed Qadah, a Dara'a representative of the National Coalition of Syrian Revolutionary and Opposition Forces, the umbrella opposition group-in-exile, said in a telephone interview from Jordan that the group was organizing buses that would return some refugees to their homes in rebel-occupied areas near Dara'a starting as early as this Sunday.
"We need them to return and rebuild their towns," he said. "We will start with the youth and young men and activists who are needed to run the towns, and then later the kids and families will return."
Andrew Harper, the top official for the United Nations refugee agency in Jordan -- where two-thirds of the more than 300,000 refugees are from the Dara'a area -- said he had seen two new trends in recent days in response to the changing situation there. More refugees are expressing interest in returning home, he said, even as the influx into Jordan has continued with as many as 2,000 people pouring over the border each night. But with what Mr. Harper called "the traditional routes" from Dara'a blocked, the number of Syrians taking the treacherous, remote desert routes to the east has tripled or quadrupled.
"The desert is a difficult, dangerous exercise to get through," Mr. Harper said, explaining that people were walking for hours until they were rescued by Jordanian military trucks, which sometimes then took two or three days driving through sand dunes to reach the Zaatari refugee camp, the main Jordanian facility for fleeing Syrians.
"We're obviously watching developments inside Syria very closely, but the foremost indicator that we've got is refugees leaving country," Mr. Harper said, "and that's still happening."
Rick Gladstone reported from New York, and Hala Droubi from Dubai, United Arab Emirates. Hania Mourtada contributed reporting from Beirut, Lebanon, and Jodi Rudoren from Jerusalem.
This article originally appeared in The New York Times.