Syria's U.N. ambassador is warning that extremist groups could use chemical weapons against the Syrian people and blame the government.

Bashar Ja'afari reiterated in letters to the U.N. Security Council and Secretary-General Ban Ki-moon, circulated Monday, that "Syria will not under any circumstances use any chemical weapons that it may have."

But Ja'afari said the government — which refers to opposition fighters as "terrorists" — is "genuinely worried" that countries supporting "terrorism and terrorists" could provide chemical weapons to armed groups "and then claim they had been used by the Syrian government."

He quoted a report in the Turkish newspaper Yurt that al-Qaida members are producing chemical weapons in a laboratory near the Turkish city of Gaziantep "that they are threating to use against Syrian civilians."