The new deployment of two additional RAF Tornados came as Cameron visited RAF Akrotiri in Cyprus, where he also met British military personnel, Xinhua quoted Downing Street as saying in a statement.
"Royal Air Force Tornado GR4 aircraft have been in action over Iraq" as part of international operations against IS, also known as ISIL, the statement added.
On Thursday, the first two Tornados sent by Britain had conducted a precision bomb attack on an armed IS truck in Iraq, British ministry of defence said. The precision attack on the truck, conducted overnight with a Paveway IV guided bomb, was successful.
Britain's House of Commons voted in favour of airstrikes in Iraq
On Wednesday, the first two Tornados on patrol over northwest Iraq were tasked to assist Kurdish ground forces. The aircraft pinpointed the location from which IS militants were "directing heavy fire" on the Kurdish troops and conducted a precision strike with Paveway IV guided bombs.
Britain's first bombing strikes on an IS heavy weapon position, conducted by RAF in Iraq Tuesday, were also successful, according to the assessment announced by the ministry.
Last week, Britain's House of Commons voted in favour of a government motion on airstrikes in Iraq against IS after nearly seven hours of debate, which ended up with a vote of 524 to 43.
Despite an overwhelming parliamentary support for military action against IS militants, the motion ruled out deploying British troops in ground combat operations.