Following the outbreak of the US-Israeli war on Iran at the end of February, groups operating under the banner of the "Islamic Resistance in Iraq" carried out repeated drone and rocket attacks on US interests in the country.

Washington, in turn, bombed facilities and bases belonging to the groups, including Kataeb Hezbollah, killing dozens of their members.

Since taking office in mid-May, Iraqi Prime Minister Ali al-Zaidi has pledged to restrict weapons to the hands of the state.

But in a statement on Saturday, Kataeb Hezbollah security chief Abu Mujahid al-Assaf said "jihadist action is today a collective duty, and we will carry it out on behalf of the brothers who have decided to abandon it".

While some factions have shown willingness to operate under state institutions, others, like Kataeb Hezbollah, refuse to discuss disarmament under US pressure.

Assaf suggested that Kataeb Hezbollah was willing to work with those other groups, and was "also prepared to pay for" weapons they no longer needed.

He said his group was ready "to cooperate and play a constructive role" by supervising the transfer and storage of weapons, and receiving specialised weapons such as cruise missiles, for which "there are no experts within state agencies".

Kataeb Hezbollah insists it will not discuss its weapons so long as foreign forces remain deployed in Iraq's northern Kurdistan region as part of a US-led international coalition formed in 2014 to fight jihadists.

The coalition is scheduled to end its mission in the Kurdistan region by September.

Earlier this month, a senior US State Department official had demanded Iraq take "concrete actions" on pro-Iran armed groups, preconditioning renewed support on "expelling terrorist militias from any state institution" and cutting off payments to them.