Iran says the US will face "harsh consequences" if it intervenes in Syria.

Iran's deputy Chief of Staff Massoud Jazayeri is warning of "vengeance" if America becomes involved in the conflict.

Barack Obama has pledged a "serious response" over claims that the Syrian army used chemical weapons against civilians.

US Defence Secretary Chuck Hagel says the US military is ready to take action against Syria.

Last night Obama and British Prime Minister David Cameron discussed the alleged attack and ordered officials to examine all options.

Yesterday, British Foreign Secretary William Hague said that the "atrocity" in Syria "was a chemical attack" carried out by Assad forces.