Seven UK terror plots 'stopped' in last six months: Cameron

British security services have foiled around seven terror plots since June with fighters returning from Syria posing a growing threat, Prime Minister David Cameron said Monday.

 "Our security and intelligence services have stopped something like seven attacks in the last six months, albeit attacks planned on a smaller scale" than Friday's attacks in Paris, he told BBC Radio 4 from Turkey.

 "We have been aware of these cells operating in Syria that are radicalising people in our own countries, potentially sending people back to carry out attacks," he added.

 Security services have spent a "long time" working out how to deal with multiple coordinated attacks on the street, but will have to go "right back to the drawing board" after the Paris attacks, which killed at least 129 people.

 "It was the sort of thing we were warned about," said the prime minister.

 Cameron added there were "hopeful signs" from Saturday's talks in Vienna on Syria that progress was being made on how to deal with the Islamic State (IS) group.

 "You can't deal with so-called Islamic State unless you get a political settlement in Syria that enables you then to permanently degrade and destroy that organisation," he said.

 However, he repeated that any settlement must include the removal of Syrian President Bashar al-Assad, a sticking point between the West and Russia.