Britain may extend anti-IS air campaign to Syria

British Prime Minister David Cameron has raised the possibility that the UK might launch airstrikes against Islamic State group (IS, formerly known in ISIS) positions in Syria.

Speaking in parliament, Cameron said "we need to crush IS in Syria and Iraq" questioned whether UK military operations might be extended to the extremist group's territory in Syria.

The Royal Air Force (RAF) is part of an international anti-IS coalition but its air strikes are limited to Iraq.

"We must deal with the security threat at source, whether ISIL (IS) in Iraq and Syria or other extremist groups around the world," he said.

IS controls 50 percent of Syrian territory and its de facto capital Raqqa lies in the east of the country.

Cameron added that the RAF are delivering the second largest number of airstrikes in Iraq and that it also contributed to nations striking IS in Syria with "airborne intelligence and surveillance assets".

The comments come after 30 British tourists were shot dead on a Tunisian resort by an IS-linked or inspired gunman on Friday.

Cameron has promised to tackle IS abroad and extremism in the UK through a new statutory body.

"If we need to act to neutralise an imminent threat to the UK, we will always do so," he told MPs.

Cameron attempted to persuade parliament to agree to RAF airstrikes against the Syrian regime in 2013, after a suspected regime gas attack on a Damascus neighbourhood. 

The prime minister met a humiliating defeat after Labour and some Conservative MPs voted against military intervention in Syria.

The UK is traing anti-Assad rebel fighters to battle IS in Syria, but unlike the United States it has not supported Kurds and opposition groups with airstrikes inside Syria.