Britain intensifies drone strikes against IS in Syria, says fight 'not over'

Britain's air force had its busiest month since February bombing Islamic State targets in Syria, as the UK defence secretary says the fight against the terror group "is by no means over".

RAF Tornado jets and Reaper drones destroyed a large number of IS "command posts, tunnel networks and weapons caches" in September, hitting targets at a rate of more than one per day, the Ministry of Defence said late on Sunday.

"The fight against Daesh is by no means over and we must continue to stand up for our people and our partners, to ensure their abhorrent and poisonous ideology does not spread to our streets," Gavin Williamson said, using the Arabic acronym for IS.

He added strikes against IS would continue "as long as they pose a clear and immediate threat to our national and international security".

In May the ministry said the RAF has conducted more than 1,600 air strikes in Iraq and Syria - second only to coalition leaders the United States.

Britain has nearly 1,400 military personnel in the region providing support to local partners, it said.

That month, London for the first time confirmed a civilian death as a result of a British strike on IS in Syria, but the real figure for direct civilian casualties for UK operations may be significantly higher according to Professor Michael Clarke, chair of the parliamentary drones group.

The British parliament authorised air strikes against IS in Iraq in September 2014, and just over a year later backed air strikes against the militants in Syria. 

IS has lost large swathes of territory it captured in 2014. As they lose more of their self-proclaimed "caliphate", militants are expected to revert to guerrilla tactics.

More than 350,000 people have been killed and millions displaced since Syria's war started in 2011 with the brutal repression of anti-government protests.