File photo of UK Prime Minister David Cameron (Reuters)

Prime Minister David Cameron on Wednesday condemned anyone considering travelling to fight in Iraq and Syria with Islamic State, saying they would be treated as an enemy of Britain.Britain has raised its terrorism alert to its second-highest level and has said Islamic State militants battling for territory in Syria and Iraq pose a grave security risk.Mr Cameron told his Conservative party conference on Wednesday he would do everything possible to stop people from travelling to Iraq and Syria to fight alongside Islamist militants, and from returning home."If you try and travel to Syria or Iraq, we will use everything at our disposal to stop you taking away your passport, prosecuting, convicting, imprisoning and even if you're there already we may even prevent you from coming back," he said."You have declared your allegiance, you are an enemy of the UK and you should expect to be treated as such."

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The British government says at least 500 of its citizens are currently involved in the conflict in addition to 250 who have already returned.