The Syrian army has captured a key southern town from rebel forces after weeks of fierce fighting, state media and activists say.

The fall of Sheikh Maskin on Monday means that government forces will strengthen their hold on Deraa province, while cutting off rebel factions from key supply lines.

Deraa, the scene of the earliest protests against the Syrian government in 2011, contains routes crucial to both the Syrian army and rebel fighters.

"The town is very important for both sides. They have both fought fiercely. Now, by taking it, the regime has cut off the rebels links between eastern and western Deraa," said Rami Abdulrahman, head of the UK-based Syrian Observatory for Human Rights, which tracks violence in the country through a wide network of local sources.

"The destruction in the town is huge."

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The Observatory said fighting involved government troops backed by fighters from the Lebanese Shia movement Hezbollah, as well as air support from Russian fighter jets.

Rebel groups involved in the battle include al-Nusra Front and some aligned with the Western-backed Free Syrian Army.

The Syrian state news agency, SANA, said the army had taken full control of the town and dismantled explosive devices planted by the rebels.

Rami Khouri, from the American University of Beirut, told Al Jazeera that military help from Russia, Iran, and Hezbollah over the past year had turned the tide for government forces.

"Without these three support groups, the Syrian government would probably have vanished because they were really in bad shape about a year ago," said Khouri.

"There's a shifting pattern of control on the ground and it's important because when the [peace] talks go ahead in Geneva, and if they achieve ceasefires, who controls more land will gain more political, economic, and humanitarian power."

Juan Cole, a Middle East analyst at the University of Michigan, told Al Jazeera that recent gains by government forces in Syria's south were significant, considering rebels once controlled about 70 percent of Deraa province.

Cole also underscored Russia's role in the advance.

"Largely because of Russian air intervention, the rebels are being scattered. Things have just turned around 180 degrees for the regime since the Russians came in … Now there is a significant reversal that will affect the rebels' logistics," said Cole.

Before Sheikh Maskin, the army, backed by Russian strikes, recaptured another key rebel base - the town of Rabia in the northern province of Latakia. It was the last rebel-held town in the province and provided an important supply route to Turkey.

Peace talks

A Syrian government advance on Deraa began late in December and Sheikh Maskin's fall comes amid international efforts to bring opposing factions to the negotiating table.

On Monday, Staffan de Mistura, the UN special envoy for Syria, said that peace talks originally scheduled to start on Monday would be pushed back to Friday.

The proposed Geneva 2 peace effort has been blighted by disagreements over which rebel groups should be allowed to attend.

The talks will also exclude al-Nusra Front, which is al-Qaeda's affiliate in the country, as well as the Islamic State of Iraq and the Levant (ISIL) group, which controls most of Syria's eastern half.

Russian Foreign Minister Sergey Lavrov on Tuesday argued strongly against Turkey's demand to keep a leading Kurdish group out of Syria's peace talks, and said he expected the UN envoy to resist "blackmail" by Turkey and others, reflecting the sharp differences that remain.