The Free Syrian Army pledged on Wednesday to punish atrocities amid outrage over a video showing the mutilation of a corpse, as the regime ruled out discussing President Bashar al-Assad’s departure in negotiations. The mainstream rebel group made the statement after a gruesome video of an alleged rebel fighter cutting out and apparently eating the organs of a regime soldier emerged online. “Any act contrary to the values that the Syrian people have paid their blood and lost their homes [for] will not be tolerated, the abuser will be punished severely even if they are associated with the Free Syrian Army,” the main rebel group said in a statement. It said field commanders had been instructed “to begin a prompt investigation into the matter in which the perpetrator will be brought to justice”. Investigations would also be held into whether the rebel in the video is a member of the Free Syrian Army or not, it said. The man in the video, identified as Khalid al-Hamad, defended his actions in an interview with Time Magazine, saying he was driving to them by footage on the dead soldier’s phone, showing him “humiliating” a naked women and her two daughters. He expressed sectarian hatred of all members of the Alawite community, the religious minority to which Assad belongs. His actions were also condemned by the opposition Syrian National Coalition, as well as the US State Department and UN rights official. The gruesome incident raised new fears about the potential for grisly sectarian violence in Syria. The Britain-based Syrian Observatory for Human Rights reported on Tuesday that three captured army officers had been summarily executed in the northern city of Raqa by fighters of the Al-Nusra Front. Amid the turmoil on the ground, the international community continued to push for talks on a political solution to the conflict. US Secretary of State John Kerry urged Syria’s president not to squander the opportunity to come to the table for negotiations, insisting “enormous plans are being laid.” But while Kerry said Russia had informed him that Syria has already chosen envoys for the conference, Syrian officials insisted that Assad’s departure - a key opposition demand - was not on the table. “Syria will not accept any dictate and its friends will not accept it either,” Syrian deputy foreign minister Faisal Muqdad told Syrian state television late Tuesday. His comments echoed those made earlier by Syrian information minister Omran al-Zohbi. “The ones who decide who is president of the country, what form the government takes and how internal processes are carried out are the Syrian people and the ballot box,” he told Hezbollah’s al-Manar television. Kerry and his Russian counterpart Sergei Lavrov announced plans for a new conference last week, intended to build on a deal agreed last year in Geneva. The deal called for an halt to the violence that is now in its third year, and a transitional government, but made no call for Assad’s departure. Jordan said on Tuesday that it would host a meeting of the largely anti-Assad “Friends of Syria” group of Western and Arab states, which is likely to focus on the conference. Diplomats anticipate that the gathering could be held in early June, possibly also in Geneva. Kerry said he spoke Tuesday with the chief of staff of rebel Free Syrian Army General Salim Idris, whom he said is “committed to this negotiation process.” Among those holding talks in the Russian capital was Israeli Prime Minister Benjamin Netanyahu, who met with Russian President Vladimir Putin on Tuesday. Putin’s official spokesman Dmitry Peskov said Israel had raised the issue of Russian weapons supplies to its ally Syria and that Moscow had defended the deliveries. “The issue was raised. The Russian Federation presented its arguments, which are well known,” Russia’s Interfax news agency quoted Peskov as saying. Israel wants Russia to halt supplies of S-300 ground-to-air missiles that could complicate any future air attacks of the sort Israel has already carried out against the Syrian regime. Putin, for his part, warned against any destabilising moves in the Middle East, days after the latest Israeli strikes. The Observatory watchdog said on Tuesday that at least 94,000 people have been killed in the Syrian conflict, revising upwards a previous toll of 82,000.