BBC news with Jerry Smit.

Turkish artillery unit has fired on Syria for the first time since the Syrian conflict began 18 months ago. It came after a

mortar

bomb fired from inside Syria killed 5 Turkish citizens. James Reynolds reports from the Turkish-Syrian border.

It is not immediately clear what Turkey was intending to hit. It comes in response to the killing earlier in the day of five Turkish civilians in the town of Akcakale. A mother and three of her children were among the dead when a shell landed. Over the past year, the government of Prime Minister Recep Tayyip Erdogan has strongly supported the Syrian opposition. But at the same time, Mr. Erdogan has not wanted his country to fight Syria directly, but the killing of Turkish civilians along the border may have made him reevaluate it that policy.

Nato has described the Syrian action as a

flagrant

breach of international law and said it

stood by

Turkey - a Nato member.

At least 31 people have been killed and dozens injured in a series of huge bomb explosions in the Syrian city of Aleppo in an area controlled by government forces. A local reporter at the scene told the BBC that there were four car bombs, two of them exploded near a police officer's' club in a hotel

tearing off

its

facade

.

Riot police in the Iranian capital Tehran have clashed with hundreds of people including many currency traders protesting against the government's failure to stop the value of the Iranian rial from plunging to record lows. Police