Syrian government forces have overrun rebels in a town northeast of Damascus, strengthening President Bashar al-Assad's grip on territory around the capital.

The town - Adra al-Omalia - is about 30km from central Damascus but far from parts of Syria where the United States has launched air strikes against fighters from the Islamic State of Iraq and the Levant (ISIL).

Syrian state TV on Thursday said the armed forces had "imposed their control over the town of Adra al-Omalia and eliminated a number of terrorists." Troops were combing the area and clearing out explosives planted by armed groups, it added.

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Assad's forces, backed by the Lebanese Shia movement Hezbollah, have been gradually extending control over a corridor of territory from Damascus to the Mediterranean coast this year, seizing towns and villages along the main north-south highway and in the mountainous Qalamoun area along the Lebanese border.

The advances in Adra al-Omalia show that the government is continuing to press that campaign as US-led forces bombard ISIL positions elsewhere in the country.

The Syrian Observatory for Human Rights, a UK-based monitoring group, confirmed the government had taken control of Adra al-Omalia after clashes with rebels including some from the Nusra Front, al-Qaeda's affiliate in Syria, whose positions have also been hit by US air strikes.

The Observatory, which monitors the conflict through a network of sources, earlier said at least 29 people - 18 of them rebel fighters - died during fighting on Wednesday between rebels and government forces in the outskirts of Damascus.

State TV broadcast what is said was live footage from the town showing soldiers standing in the area near buildings that had collapsed or were smashed up.

Many Syrian activists and rebels have criticised the US for focusing on striking ISIL and other armed groups while doing little to bring down Assad.

Syria's conflict started as a peaceful protest movement but, after a government crackdown, turned into a war that has killed more than 190,000 people over more than three years.

Fighting still regularly kills nearly 200 people a day.

Source: Al Jazeera and agencies