AMMAN: The Syrian army backed by Russian jets escalated bombing of the last rebel bastion on the eastern outskirts of Damascus as they prepared to break a siege of an army base encircled by opposition forces, residents and witnesses said on Wednesday.

They said the army was amassing elite forces to prepare for a major assault on the Military Vehicles Administration, which is besieged by rebels.

At least 200 troops were believed to be trapped within its sprawling, heavily defended grounds.

State media did not report the assault but said “terrorists” had fired mortars on residential areas in Harasta and the army responded by strikes in Eastern Ghouta that led to losses in the ranks of the insurgents. No further details were given.

Emilie Koenig, a Frenchwoman suspected of recruiting fighters for the Daesh group who figured on US and UN blacklists, has been arrested by Kurdish forces in Syria, her mother said on Tuesday.

The 33-year-old daughter of a gendarme is “being held in a Kurdish camp and has been interrogated and tortured,” her mother told Ouest-France newspaper.

Koenig went to Syria in 2014 and three of her children were born in that country.

She was put on the UN list of the most dangerous fighters and a year later figured on a US terror list.

A Russian helicopter crashed in Syria on New Year’s Eve killing both pilots following a technical fault, Moscow’s defence ministry said Wednesday.

The Mi-24 military helicopter was flying to Hama, northwestern Syria, and there was no firing from the ground, agencies quote the ministry as saying.

“Both pilots died in a hard landing 15km from the air base,” the ministry said, adding that a technician had been injured and taken to another air base at for emergency treatment.

The investigative blog Conflict Intelligence Team (CIT) quoted a post from Forumavia aviation forum saying the helicopter had tripped over power line wires and crashed while escorting a convoy.

The post did not specify whether the helicopter was escorting a humanitarian convoy or combat unit and the defence ministry did not give any further details.

Civil defence sources said that in four days of heavy aerial strikes since Friday 38 civilians have been killed and at least 147 people have been injured. Five civilians were killed on Tuesday.