BEIRUT: Syrian rebels fought back Wednesday against a government offensive near Aleppo that appeared to pour cold water on Staffan de Mistura’s announcement of a government readiness to halt hostilities in the northern city.

The surprise offensive began early Tuesday, and hours before U.N. envoy de Mistura informed the Security Council that President Bashar Assad was willing to suspend the bombing of Aleppo for six weeks.

Anti-regime activists said rebels had reclaimed control of a village, Ratyan, seized by government forces and paramilitary allies in the campaign, and claimed that they had taken two other nearby villages, while pro-government sources denied this.

The Syrian Observatory for Human Rights, a monitoring group based in Britain, said the rebels took prisoner at least 15 pro-government fighters during the battle in Ratyan.

Anti-regime activists posted video footage purporting to show a building surrounded by rebel fighters, and the 19 soldiers who were later taken prisoner.

Activists and rebel groups in the city also accused the government side of committing a massacre of approximately 30 civilians in Ratyan shortly after the offensive began Tuesday.

Pro-government sources also said that several dozen fighters, some of whom were from Hezbollah, had managed to escape the rebels during the battles and reach the nearby towns of Nubl and Zahraa, Shiite-majority areas that have been blockaded by the rebels.

Fierce clashes also took place in the Mallah region outside Aleppo and activists posted video footage purporting to show the capture of a regime tank during the battle.

Estimates of the total fatalities on both sides have topped 100 and many photographs and video footage has been circulated purporting to show the corpses of pro-regime fighters, whom the Observatory and local activists say include a large number of non-Syrian militiamen, from Iran, Lebanon, Iraq and Afghanistan.

The fighting came after de Mistura told the Security Council that President Bashar Assad’s government “has indicated to me its willingness to halt all aerial bombing ... in addition to artillery shelling for a period of six weeks all over the city of Aleppo, as of a date that we will be announcing in Damascus.”

De Mistura said he would now prepare a trip to Damascus and “hopefully” to Aleppo to discuss the latest moves.

“Let’s be frank – I have no illusions because based on past experiences this will be a difficult issue to be achieved,” he added.

Two leading alliances of rebel factions with a strong presence in Aleppo, the Revolutionary Command Council and the Shamiah Front, have already dismissed de Mistura’s efforts after his statement last week that Assad was “part of the solution” in Syria.

An anti-regime activist in Aleppo, who requested anonymity, told The Daily Star that ‘I personally was supportive of the initiative [by de Mistura], but after [Assad] expressed his readiness and at the same time he let the sectarian militias loose, I don’t have any more confidence [in the regime].”

A source from the Shamiah Front agreed, saying that de Mistura’s efforts, particularly after the latest offensive, were unlikely to gain much support.

“For four years we haven’t believed a word the regime says,” the source said. “De Mistura was near Douma [a rebel-held suburb of Damascus], while it was burning ... he’s a partner of Assad.”

The government offensive also began on the day Washington and Ankara reportedly reached a tentative agreement to train a mainstream Syrian rebel force, but one dedicated to battling ISIS militants.

The Pentagon said it had screened about 1,200 rebels who could participate in the program. Press secretary Rear Adm. John Kirby said they would continue to be screened as they move through the process and could go to any of the three training facilities in Turkey, Saudi Arabia and Qatar – once those sites are set up.

Kirby said the rebel fighters come from several moderate groups in Syria and that the training would focus on basic military equipment and skills.

In Riyadh, representatives of 26 countries gathered to discuss their coalition’s efforts to fight ISIS, with the meeting expected to cover the Syrian war as well.