Britain warned Syrian President Bashar Assad on Monday that "no option is off the table" over the possible arming of Syrian rebels and said it would press the European Union to make further changes to its weapons embargo.
In a statement to parliament, Foreign Secretary William Hague said the EU should rethink its embargo on sending weapons to Syria, even if it holds back from making an immediate decision on whether to arm the opposition to Assad.
"We must make clear that if the regime does not negotiate seriously at the Geneva conference, no option is off the table, Hague said. "There remains a serious risk that the Assad regime will not negotiate seriously."
Assad has poured scorn on new plans for peace talks announced by the United States and Russia two weeks ago and planned for Geneva in early June.
An entire package of European sanctions against Syria expires on June 1. Hague said the collapse of Syria was moving closer each week and that this would lead to a "regional catastrophe".
"The case for further amendments to the arms embargo on Syria is compelling in order to increase the pressure on the regime," he said.