A Syrian opposition group on Tuesday said rebels have seized control of a town along the Turkish border where the army and militias loyal to the regime are based.
"The rebels managed to control, by the early hours of the morning, all of Harem region including the strategic castle, which was the last stronghold of the Syrian government forces and its militia," Rami Abdel-Rahman, head of the Syrian Observatory for Human Rights told dpa.
Activists reported that some 700 Syrians have crossed the border into Turkey over the last 24 hours.
Clashes between government and rebel forces were reported from areas near the airport in the capital Damascus. Activists said rebels killed a ranking-intelligence officer in the suburb of Jaramana late Sunday.
Syria's ambassador Riad Haddad meanwhile vehemently denied rebel reports that troops have used chemical weapons in the central province of Homs.
The Observatory had said several people died as a result of a poisonous gas used by the army.
"Such reports are completely untrue... This was clearly a provocation and part of a plan to exert psychological pressure on the Syrian government," Haddad said in Moscow, according to Interfax news agency.
Russian Foreign Minister Sergei Lavrov said Monday it would be "political suicide" for the regime of President Bashar al-Assad if it used chemical weapons against the opposition.