Syria crisis: 'Scepticism about chemical attack claims'
Syrian rebels and the government have accused each other of firing chemical weapons, reportedly killing at least 25 people in the north of the country.
A Syrian minister said it was a "dangerous escalation" and the "first act" of a new rebel authority.
However, both a chemical weapons monitoring body and the US said there was no evidence they had been used.
The BBC's James Reynolds says that there is also some scepticism among analysts regarding the claims.