MOSCOW- Russia accused Syrian rebels of using chemical weapons in an attack on Tuesday and said it was an extremely alarming and dangerous development."A case of the use of chemical weapons by the armed opposition was recorded early in the morning of March 19 in Aleppo province," the Russian Foreign Ministry said after President Bashar Assad's government and rebels accused each other of launching a deadly chemical attack. "We are very seriously concerned by the fact that weapons of mass destruction are falling into the hands of the rebels, which further worsens the situation in Syria and elevates the confrontation in the country to a new level," the ministry said in a statement.Britain said earlier on Tuesday it was aware of media reports about a chemical weapons attack in Syria, adding that the use or proliferation of chemical weapons there would demand a serious response from the international community."The UK is clear that the use or proliferation of chemical weapons would demand a serious response from the international community and force us to revisit our approach so far," a Foreign Office spokeswoman said.Turkey, meanwhile, rejected an accusation from Syria on Tuesday that Turkey bore responsibility for a possible chemical attack in the northern province of Aleppo."This is a baseless accusation, the Syrian government has accused Turkey in the past as well," a Turkish government official told Reuters.Syrian Information Minister Omran Zoabi said earlier that Turkey and Qatar, which have supported rebels fighting President Bashar Assad, bore "legal, moral and political responsibility" for the attack, state television reported.Syria's Information Minister Omran Zoabi said on Tuesday the country's armed forces would never use internationally banned weapons, after the government and rebels traded blame for what both sides said was a chemical weapon attack near Aleppo."Syria's army leadership has stressed this before and we say it again, if we had chemical weapons we would never use them due to moral, humanitarian and political reasons," Zoabi said in a televised news conference."Our armed forces absolutely could not use, not now, nor at any time, nor in the past, any weapon banned by international law."