BEIRUT - Syria's army staged a counterattack in northeastern Damascus on Monday, but there were conflicting accounts of how much ground it regained after Sunday's rebel assault.
A Syrian military source and a war monitor said the army had recaptured all the positions it had lost, but rebels said they were still holding on to some of their gains despite heavy aerial bombing that had forced them to retreat.
The army's advance involved heavy fighting and intense air strikes, the Syrian Observatory for Human Rights and a military media unit run by the army's ally Hezbollah said.
A Reuters witness saw war planes circling in the sky above northeast Damascus, mortar fire, and a street with a line of burned-out cars from the fighting in the Jobar and al-Qaboun districts.
The Observatory, a British-based war monitor that collects information from a network of sources across Syria, said heavy fighting continued and that the army had unleashed more than 500 air raids and artillery strikes. The Hezbollah-run military media unit said that air raids were aimed at rebel supply lines. Rebels had attacked in Jobar to relieve military pressure after their loss of ground in nearby Qaboun and Barza, a commander from the Failaq al-Rahman group which is fighting there said on Sunday.
The intensity of the Syrian army's counterattack forced the rebels to retreat on Sunday night from at least 60 percent of the areas they captured that day in an industrial area that separated Qaboun from Jobar, a rebel spokesman said.
"Today the clashes are difficult and there is no progress in the face of this ferocious bombardment that is not just limited to the frontline but all night the regime was shelling the cities and towns in Eastern Ghouta in retaliation," Wael Alwan, the spokesman for Failaq al Rahman, told Reuters.
Syrian President Bashar al-Assad and his army, along with allied Russian, Iranian and Shi'ite militia forces, have put rebels on the back foot with a steady succession of military victories over the past 18 months, including around Damascus.
For rebels, however, their first such large scale foray in over four years inside the capital signalled they were still able to wage offensive actions despite their string of defeats.
"This battle gave hope we can stand up to the regime's military machine ... It was again us going back to a sort of balance of force and not just defending ourselves," Alwan said.
Rebels still hold a large, heavily populated enclave in the Eastern Ghouta district of farms and towns to the east of the capital, as well as some Damascus districts in the south, east and northeast of the city.
The most recent fighting has focused on the areas around Qaboun and Barza, which the army has isolated from the rest of the main rebel enclave of Eastern Ghouta and the eastern districts of Damascus.
Meanwhile, Russia's foreign ministry on Monday said it had summoned Israel's ambassador over air strikes close to Moscow's forces near the historic Syrian city of Palmyra.
Deputy foreign minister Mikhail Bogdanov told Interfax news agency that Ambassador Gary Koren was summoned on Friday and "asked about" the strikes.
The ministry "expressed concern" about the action taking place near Russian military locations, Bogdanov said.
Russia - which is conducting its own bombing campaign in Syria in support of President Bashar al-Assad - said earlier this month that more than 180 of its troops have started demining around Palmyra's ancient monuments.
Russia and Israel have set up a "hotline" aimed at avoiding air clashes over Syria and Bogdanov said Moscow "would like this channel to work more effectively" to ensure no "misunderstanding on who is doing what."
Israeli warplanes struck several targets on Friday, prompting retaliatory Syrian missile launches, in the most serious incident between the two countries since the war began six years ago.
Israel's military said it had been targeting weapons bound for Lebanon's Hezbollah movement, which backs Assad in Syria.
Syria's military said it had downed an Israeli plane and hit another as they were carrying out pre-dawn strikes near Palmyra, the famed desert city it recaptured from militants this month.
The Israeli military denied that any planes had been hit.
On Sunday, Israeli Defence Minister Avigdor Lieberman threatened to destroy Syria's air defence systems "without the slightest hesitation" if there was a similar incident.
Russia has deployed its own high-tech missile defence systems to Syria to protect its forces there.
Reuters/AFP