Iraqi forces admit they have faced fierce resistance from Isis fighters and want to user thermobaric weapons to drive them out of tunnels and bunkers

This article is more than 3 years old

This article is more than 3 years old

The Iraqi government has asked the UK to help its military obtain powerful thermobaric weapons to drive Islamic State fighters out of tunnels in their northern Iraqi stronghold of Mosul.

The request is understood to have been put to the Ministry of Defence on Monday.

The MoD confirmed that defence minister Mike Penning met Iraqi officials but says the British military does not hold such weapons, adding that a formal written request could be put to the 67-nation coalition fighting Isis. All requests for weapons are supposed to be processed centrally by the coalition.

The Iraqi army has admitted it is facing fierce resistance from Isis fighters inside Mosul. After weeks of deadly street-by-street fighting, it says it has liberated a third of the east of the city, meaning that Isis has been removed from a sixth of the city’s area.

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Reports have already appeared that Iraqi troops fighting for Mosul’s outskirts have access to 60-tonne, Russian-made TOS-1A artillery tanks capable of firing thermobaric weapons.

Pictures have already appeared of the tank on the road to Mosul, and Shia militias, known as the popular mobilisation units (PMUs) or Hashd al-Shaabi have promised to use them against Isis fighters.

Justin Bronk, research fellow at the Royal United Services Institute defence thinktank, explained: “Thermobaric weapons work on the principle of finely powdered fuel scattered by a charge and then ignited.

“The idea is that the entire explosive weight in a warhead can be a fuel rather than a conventional explosive mixture which is around 30% fuel and 70% oxidiser.

“They kill primarily through the powerful and extremely fast blast pressure wave which they create on ignition, as well as the secondary effect of almost instantly sucking up all the oxygen in the immediate vicinity of the blast.

“Both of these effects are significantly enhanced when they occur in combined spaces, which is why they are particularly lethal against tunnels and bunker complexes.”

The Iraqi ambassador to London, Salih Husain Ali al-Tamimi, briefed Westminster MPs this week that the Iraqi forces may need further air support to close all the corridors being used by Islamic State fighters fleeing the city for the Syrian city of Raqqa, the other Isis stronghold.

He said that only 40,000 people had fled Mosul so far, but as the liberation battle continued, the number could rise to 500,000. He said civilians have been advised to stay in the city until an area is cleared.

Four refugee camps have been established and six more are in the process of being built. He added: “Islamic State are using civilians as human shields, and since the Iraqis are avoiding civilian casualties it will take time to liberate the city. The intense nature of the battle and the use of tunnels meant the liberation will take many more weeks.”

Three thousand Islamic State fighters are estimated to remain inside Mosul, and the Iraqi ambassador was closely cross-examined on guarantees that the PMUs would not seek to undertake sectarian reprisals against the Sunni population in Mosul.

He insisted the PMUs were working under the full control of the Iraqi government and should not be regarded as an unofficial militia.

Defence sources said the single greatest difficulty in the close urban warfare under way in Mosul was the elaborate network of hidden tunnels under the city from which Isis fighters mount attacks on Iraqi soldiers, including sniper fire.

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Villages recaptured from Isis over the past month by Kurdish peshmerga and Iraqi army forces on the road to Mosul have been riddled with tunnels, many of them booby-trapped.

One Iraqi counter-terror expert has said that the Iraqi forces in Mosul are fighting a war on two fronts, one overground and another underground. One tunnel outside Mosul was up to six miles long. The original tunnellers sometimes appeared to have employed drills originally designed for mining operations or oil fields.

Col John Dorrian, a spokesman for the US-led coalition forces supporting the operation, said airstrikes had so far destroyed 59 suicide car bombs and over 80 tunnels. Grenades are currently the most effective way of trying to destroy tunnels, but they have limited range.

In recent months the UK has started using Storm Shadow cruise missiles fired from RAF Tornados and capable of hitting huge identified Islamic State bunkers.

But such massively destructive weaponry would not be appropriate to use in the context of Mosul, and has anyway been criticised by the west when used by the Syrian airforce in east Aleppo.

A British Ministry of Defence spokesman said: “The UK does not have thermobaric weapons and will not provide them to third parties. All requests for assistance and equipment for Iraq are coordinated through the coalition against Daesh.”