Syria says could use chemical arms against foreign intervention

International pressure on President Bashar al-Assad has escalated dramatically in the last week, alongside a rebel offensive in the two biggest cities and a bomb attack which killed four members of his inner circle in Damascus.

Defying Arab foreign ministers who yesterday offered Assad a "safe exit" if he stepped down, the Syrian leader has launched fierce counter-offensives, reflecting his determination to keep power as a 16-month uprising enters its most violent phase.

Foreign Ministry spokesman Jihad Makdissi said the army would not use chemical weapons to crush rebels but could use them against forces from outside the country.

"Any chemical or bacterial weapons will never be used ... during the crisis in Syria regardless of the developments," Makdissi said. "These weapons are stored and secured by Syrian military forces and under its direct supervision and will never be used unless Syria faces external aggression."

Damascus has not signed a 1992 international convention that bans the use, production or stockpiling of chemical weapons, but officials in the past had denied it had any stockpiles. Western countries expressed immediate alarm.

"Given the escalation of violence in Syria, and the regime's increasing attacks on their people, we remain very concerned about these weapons," White House spokesman Tommy Vietor said.

British Foreign Secretary William Hague said it was a "complete illusion" that Syria faced any external threat and it was unacceptable to say it might use chemical weapons in any circumstances.

German Foreign Minister Guido Westerwelle said it was "outrageous to threaten to use chemical weapons" and UN Secretary General Ban Ki-moon said he was very concerned Syria may be tempted to use unconventional weapons.

Western and countries and Israel have also expressed fears chemical weapons could fall into the hands of militant groups as Assad's authority erodes. Israel has publicly discussed military action to prevent Syrian chemical weapons or missiles from reaching Assad's Lebanese Shi'ite militant allies Hezbollah.