Syria conflict: Troops 'cross into IS-held Raqqa province' Published duration 4 June 2016 Related Topics Syrian civil war

image copyright Reuters image caption A US-backed alliance is also attempting to take Raqqa, in what appears to be a pincer movement

Syrian troops have crossed into Raqqa province, nearing the capital of so-called Islamic State, activists say.

The UK-based Syrian Observatory for Human Rights said heavy Russian air strikes had helped the offensive. There is no Syrian or Russian confirmation.

A US-backed alliance of Syrian Kurdish and Arab fighters started a campaign in May to expel IS militants from land north of Raqqa.

IS seized the city in 2013 from rebels opposed to President Bashar al-Assad.

The jihadist group quickly established its headquarters there and began imposing its vision of a state, implementing a strict interpretation of Islamic law.

It proclaimed a "caliphate" in 2014.

The Syrian Observatory said there had been clashes with IS militants on the Athria-Tabqa road as the Syrian troops moved from Hama province in the south-west.

The Syrian military were trying to reach Lake Assad and the main road linking Raqqa to Aleppo.

Tabqa is home to a key airbase taken by IS in August 2014.

To the north of Raqqa, the US-backed Syrian Democratic Forces (SDF) are believed to have deployed about 30,000 fighters as they try to force IS out of the city.

Russia has promised to co-ordinate with the SDF and the US on the offensive.

The alliance, which is dominated by the Kurdish Popular Protection Units (YPG) militia, has emerged as a key ally of the US-led coalition over the past two years, leading the fight against IS on the ground in northern Syria.