More than 170 Islamist rebel fighters, including Saudis, Qataris and Chechens, were killed Wednesday in a Syrian army ambush near Damascus, state news agency SANA reported.

The attack, apparently the deadliest against the rebels for months, took place in Eastern Ghouta, a key rebel stronghold targeted in a chemical attack in August 2013 that killed hundreds of people.

SANA said an army unit "spotted Al-Nusra Front (jihadist) and Liwa al-Islam (Islamist) terrorists" near Damascus, and "killed 175 of them and wounded several others."

Saudis, Qataris and Chechens were among the dead, it said.

State television had earlier reported "dozens" killed, mostly non-Syrians, in a "well-organized ambush" following a tip-off.

The army also seized the rebels' weapons, the broadcaster said, following the regime's practice of using the term "terrorists" to refer to the armed opposition.

Al-Nusra Front is al-Qaida's official affiliate in Syria and is committed to the overthrow of President Bashar Assad and the establishment of an Islamic state.

The Syrian Observatory for Human Rights, a Britain-based group with a network of contacts inside Syria, confirmed that dozens were killed in the ambush.

"Dozens of Islamist fighters were killed and wounded in an ambush by loyalist troops, with the help of Hizbullah, near Otaybeh village in the Eastern Ghouta area," it said.

A government security source said most of the fighters were Jordanians or Saudis, and that they had crossed over into Syria from Jordan earlier the same day.

The source said the ambush took place at around 5:00 am (0300 GMT) and killed 156 rebels. Another 10 were taken prisoner, said the source, speaking on condition of anonymity.

The Otaybeh area has seen several army ambushes in past months.

Syria's war has since March 2011 killed more than 140,000 people and forced millions more to flee.