Islamic State militants attacked Syrian army troops with mustard gas in an offensive against a Syrian military airport in the eastern province of Deir ez-Zor that borders Iraq, state media said on late Monday, April 4, according to Reuters.

Syrian state media did not disclose how many casualties were sustained in the latest drive by the hardline fundamentalist Sunni militants to capture the heavily defended airport located south of Deir al Zor city, whose main neighborhoods are under the militants control.

"The terrorists fired rockets carrying mustard gas," a statement said on state owned Ikhbariyah television station.

Deir ez-Zor is a strategic location. The province links Islamic State's de facto capital in Raqqa with its fighters in Iraq.

Amaq news agency, which is close to the militants, had earlier said Islamic State fighters had launched a wide scale attack on Jufrah village near the airport in which it said two of its suicide bombers rammed their vehicles into army defenses causing "tens of dead".

"The battles continue on more than front and posts and we pray to Allah (God) victory for his Mujahdeen (holy warriors)," an official statement by the militants said.

The UK-based Syrian Observatory for Human Rights, a monitor which tracks violence across the country, said the militants had advanced with heavy aerial strikes aimed at repelling their offensive.