Syrian regime forces advanced against rebels in Eastern Ghouta on Monday, as they moved closer to retaking the opposition enclave on the edge of Damascus.
Three weeks after launching a fierce offensive to capture the region, forces loyal to President Bashar al-Assad have overrun more than half of Ghouta, whittling down rebel territory to three isolated pockets.
Backed by Russia, the advance has battered Eastern Ghouta with air strikes, artillery and rocket fire, raising widespread international concern and prompting urgent calls for a ceasefire.
Pro-regime forces advanced again in Ghouta on Monday, using Medeira, a town captured on Sunday, as a base to push against areas closest to the capital, according to the monitor, the Syrian Observatory for Human Rights.
"The army used (Medeira) as a launching pad towards Harasta and Arbin," Observatory chief Rami Abdel Rahman said.
Regime air strikes on Monday were pounding the two towns, which lie in the western part of Ghouta, the Britain-based Observatory said.
The other two areas still in rebel hands are Douma, the region's biggest town in the north of the enclave, and the zone around Hammuriyeh and other towns to the south.
An AFP correspondent in Douma said the morning was relatively quiet in the town, allowing civilians to venture out of bomb shelters to check on the destruction in their homes or gather food.
Residents were seen queuing at a butcher shop, whose owner had slaughtered a calf that he could fatten up no further because there was nothing left to feed it.
By mid-morning, warplanes were buzzing overhead.
Syria's conflict broke out in March 2011 with peaceful protests against Assad, but a regime crackdown paved the way for a fully-fledged war.
Repeated efforts by world powers to secure ceasefires or political settlements to the conflict have failed.
At least 353,935 people have died since, including more than 106,000 civilians, the Observatory said on Monday, providing a new overall death toll for the conflict.
More than 19,800 children are among the dead, it said.
UN children's agency UNICEF on Monday reported a 50 percent increase in the number of children killed in the conflict last year, condemning "extreme and indiscriminate violence".
Rebel mortar and rocket fire has also rained down on the capital, killing two civilians on Monday in the Al-Kabbas neighbourhood, according to state news agency SANA.
More than 35 civilians have been killed in rebel fire on government-controlled zones in Damascus and its outskirts since the start of the Ghouta offensive, according to the Observatory.
The government onslaught of Eastern Ghouta began on February 18 with a ferocious air campaign followed by a ground operation that has recaptured nearly 60 percent of rebel territory.
Syrian regime troops have used siege tactics on several areas around the capital, sealing off a rebel-held town and pursuing a military operation against it before securing a deal for its evacuation.
A similar deal has been put forward for parts of Eastern Ghouta, including the town of Hammuriyeh, a negotiator and the Observatory told AFP.
The agreement would offer safe passage to rebels and civilians who wanted to leave and the town would come under government control.
The Observatory confirmed talks were taking place on Hammuriyeh, as well as the towns of Kafr Batna, Jisreen and Saqba, but said no agreement had yet been reached.
All three towns are controlled by Islamist rebel group Faylaq al-Rahman, which has repeatedly denied engaging in talks with the regime.
Most of Ghouta is held by Faylaq and by rival faction Jaish al-Islam, but jihadists once linked to Al-Qaeda also have a presence.