BRUSSELS, Dec 4 (Reuters) - Britain has told the Syrian government that any use of chemical weapons would have "serious consequences", British Foreign Secretary William Hague said on Tuesday, adding to a series of warnings from world powers.
Hague was talking after Syrian forces bombarded rebel districts near Damascus in a counter-attack aimed at stemming rebel gains around President Bashar al-Assad's power base.
International concern over Syria's intentions has been heightened by reports that its chemical weapons have been moved and could be prepared for use.
"We have become more concerned about them (chemical weapons) in recent days, for the same reasons the United States has," Hague told reporters on the sidelines of a meeting of NATO foreign ministers in Brussels.
"We have already sent our own clear private message to the Syrian regime - directly to them - about the serious consequences from the use of such weapons."
U.S. President Barack Obama said on Monday that Assad would be held accountable for any used of chemical weapons against opposition forces.
France said on earlier on Tuesday that it was aware the Syrian government was possibly moving chemical weapons on military bases and that foreign powers would be forced to act if it used such arms.
NATO Secretary-General Anders Fogh Rasmussen also said earlier on Tuesday that there would be an immediate reaction from the international community to any use of chemical weapons by the Syrian government.
Britain led a push last week to review EU sanctions on Syria every three months - instead of every year as previously - to make it easier in future to equip rebels fighting to depose Assad.
EU sanctions on Syria include an embargo on the supply of arms to the country, imposed to prevent the flow of weapons to Assad's forces. The shorter review period would make it easier to amend the embargo to allow the supply of non-lethal training and equipment to the Syrian rebels.
Western military experts say Syria has four suspected chemical weapons sites, and it can produce chemical weapons agents including mustard gas and sarin, and possibly also VX nerve agent.
"For a long time Syria has denied having chemical weapons and it's very obvious that they do have those chemical weapons," Hague said. "We have said before, earlier this year, that we would have to revisit our approach in the event of the use of chemical weapons."