The UK is sending a consignment of heavy machine guns and ammunition to Iraq's government to assist with its battle against militants from Islamic State (Isis), the defence secretary, Michael Fallon, has said.

The equipment, described as an "initial gifting package" worth £1.6m and a further £475,000 in transport costs, is scheduled to arrive in Iraq on Wednesday, Fallon said in a written parliamentary statement.

The armaments were being sent at the request of Iraq's government, and were also for use by the Kurdish regional administration, he said.

Fallon's statement also said ministers were "committed to assisting the government of Iraq", including by providing humanitarian assistance for those targeted by the militants, helping the country to repel the group's advance "and restore stability and security across the country", and tackling the broader regional and international threat faced from the group.

It added: "The Kurdish forces remain significantly less well-equipped than Isil and we are responding to help them defend themselves, protect citizens and push back Isil advances."

In a later statement, the Ministry of Defence said the military aid would include nearly half a million rounds of ammunition.

Earlier on Tuesday an RAF flight had arrived in Irbil in northern Iraq carrying non-military aid, which has so far included items such as armour, helmets and ration packs.

In the MoD statement, Fallon said: "Isil [Islamic State] militants are guilty of shocking brutality. So I am pleased that we will supply weapons to the Kurdish forces who are at the front line of combating their violent extremism.

"We have already provided body armour and other protective equipment as well as ammunition from our partners; these weapons will help the Kurdish forces in taking the fight to these barbaric terrorists."

Islamic State is making rapid progress across Iraq and Syria, in part due to the high quality of equipment enjoyed by its forces. A report by the London-based Conflict Armament Research consultancy published on Monday found the group was using large captured US-made weapons and had access to anti-tank rockets supplied by Saudi Arabia to a moderate rebel group.

The report drew no conclusions about how the weapons were sourced. However, the capitulation of the Iraqi army in northern Iraq on 10 June gave the jihadis access to military arsenals in the north of the country, which were full of US-supplied assault rifles and ammunition, as well as heavy weapons.

The report was compiled from a list of weapons captured from Isis by Kurdish militias over a 10-day period in July.

Western nations are still developing their strategy to tackle Isis in the wake of last week's Nato summit in Newport. Barack Obama is scheduled to give more details of the US response on Wednesday.

David Cameron has not ruled out British involvement in any military strikes, though he would be under pressure to seek approval from parliament before doing so. Ministers have said this will take place if there is sufficient time.