RAF war planes attacking Islamic State forces in Iraq and Syria have reported coming under attack from surface-to-air missiles, a senior British commander has said.

Tornado GR4 aircraft from the Norfolk base have been carrying out airstrikes against Islamic State targets along with Typhoon jets from RAF Coningsbury, Lincs.

Lieutenant General Mark Carleton-Smith said the superior defensive equipment deployed by the coalition meant that the militants - also referred to as Daesh - had so far failed to bring down a coalition aircraft.

'We have always made the operational assumption that the Daesh inventory might at some juncture include surface-to-air missiles,' he said.

'There have been reports of engagements - several are of United Kingdom aircraft - but to no material effect as a result of the defensive aids suites that they are carrying and the tactics the coalition employs. They detect the missile as it is launched.'

Aircraft can deploy flares to distract heat-seeking missiles and perform evasive manoeuvres when a missile is launched from the ground.

Iraqi government forces backed by the US-led coalition are 'on the cusp' of taking Islamic State's (IS) last major stronghold in the country, Defence Secretary Sir Michael Fallon has said.

Sir Michael, who has returned from a three-day visit to Iraq where he met senior government figures, said the operation to take the city of Mosul would begin 'in the next few weeks'.

Two years after the RAF began military operations against IS - also referred to as Daesh - UK warplanes were stepping up attacks on the militants' positions ahead of the offensive, striking more than 100 targets in and around the city.

'The RAF is now operating at the highest tempo in a single theatre for over 25 years,' Sir Michael said.

'There is no doubt that Daesh is facing defeat. We are on the cusp of liberating the last major city in Iraq - Mosul.

'Having spoken to the commanders of the troops involved, their self-belief and determination is very clear.

'Though Mosul is a large and complex city, it will fall and will fall soon. I expect the operation for its encirclement to begin in the next few weeks.'

Lieut Gen Carleton-Smith said coalition air strikes were keeping up the pressure on IS, destroying 'close to a billion dollars' in IS's illegally held 'cash stockpile'.

'We are disrupting Daesh command and control with targeted strikes that are restricting their freedom of movement and their logistic resupply,' he said.

Sir Michael acknowledged that the fall of Mosul would not mean the end of IS in Iraq, but said that it should be possible to drive them out of the country within the coming months.

'There remain pockets of Daesh resistance. However, we estimated at the beginning a three-year campaign. Two years on we have made significant progress. Daesh is a failing organisation,' he said.

'We ought to be able to get Daesh out of Iraq over the next few months - the remaining months of this year and next year.'

Coalition defence ministers will meet next month to discuss how to deal with the estimated 8,000 foreign nationals fighting with IS - including around 400 UK nationals - some of whom are expected to try to return to Europe.

'The partners in the coalition are very clear that their nationals who have gone off to fight and may have been involved in barbaric crimes should not be allowed to slip through the net without facing justice,' he said.

Sir Michael acknowledged that the struggle against IS in Syria was 'more complicated' but insisted that 'significant progress' had been made.