Isis capital of Raqqa
Raqqa is said to hold 3,000-5,000 Islamic State members, who live alongside an estimated 50,000 civilians who are unable to leave.Mohammed Abdul Aziz/AFP/Getty Images

The Syrian army has reportedly crossed into the Raqqa province for the first time since 2014, the Syrian Observatory for Human Rights said on 4 June. The monitoring group noted that the move was part of a major Russian-backed offensive against Islamic State (Isis) terrorists.

On 3 June, Reuters reported that heavy Russian air strikes hit Isis (Daesh) territory in eastern areas of the Hama province, which lies near the border of the Raqqa province. The army was then able to reach the edge of the Isis stronghold of Raqqa, which has acted as the militant group's de facto capital in Syria along with Mosul in Iraq.

Syrian President Bashar al-Assad's forces are now believed to be heading towards the Isis stronghold of Tabqa, which lies on the main road to the city of Raqqa and is used by Isis terrorists as a base to launch operations across Syria. According to the Independent, at least 26 IS fighters have been killed, as well as nine Syrian security forces and supporting fighters.

The Syrian army offensive is one of many big attacks on IS in recent days, with US-backed Iraqi and Syrian forces attempting to recapture several cities. On 28 May, Turkish coalition air strikes led by the US in northern Syria killed 104 militants. The recent offensives are believed to be some of the most aggressive attacks against Isis since it announced the formation of its self-declared caliphate two years ago.

However, last month activists said that Isis militants in Raqqa were using "human shields" to defend their territories from US-backed Kurdish and Arab fighters. Abdel Aziz al-Hamza, co-founder of Raqqa is Being Slaughtered Silently, told AFP news agency that militants are hiding in civilian buildings.

Aziz al-Hamza said: "They are using the civilians as cover. So you'll find them in the same building. In a civilian building, you'll fight two or three apartments for Isis fighters. They also talk of some schools as places to stay because these schools have basements, something underground, so they are protected from air strikes. And they are surrounded by civilian buildings."

Raqqa is said to be hosting between 3,000-5,000 Isis members, who are living alongside an estimated 50,000 civilians who are unable to leave. Aziz al-Hamza, who escaped the city in 2014, said that Isis terrorists do not allow anyone to leave the city.