The US has imposed sanctions on an Israeli group it says has been attacking humanitarian aid convoys heading to Gaza.

The state department said the US assets of Tzav 9 – an organisation with ties to Israeli reservists and West Bank settlers – will be frozen and Americans will be barred from dealing with it.

For several months Israeli activists have been preventing aid convoys destined for Palestinians in the Gaza strip.

On 13 May protesters were filmed attacking two trucks in the occupied West Bank, ripping bags of grain open. The vehicles were set on fire. The White House described the “looting” of aid convoys as “a total outrage”.

At the time, Tzav 9 said some of the protesters’ actions were “not in line with the values of our movement”.

But it added that “blocking the trucks is an effective and practical step in which we shout that ‘no aid passes until the last of the hostages returns'”.

The state department said on Friday that US sanctions were being imposed under an executive order on West Bank violence signed by President Joe Biden in February.

“For months, individuals from Tzav 9 have repeatedly sought to thwart the delivery of humanitarian aid to Gaza, including by blocking roads, sometimes violently, along their route from Jordan to Gaza, including transiting the West Bank,” the state department said in a statement.

It has previously sanctioned Jewish settlers involved in attacks on Palestinians as well as on Palestinian militant groups.

The Israel Defense Forces have also been accused of withholding aid – a charge it denies.

The UN has warned that over a million people in Gaza could face starvation by the middle of July unless more aid is allowed into the strip.

More than 37,000 people have been killed, and many hundreds of thousands more injured or displaced in Israel’s offensive against Hamas in Gaza, according to the Hamas-run health ministry.

The war began after Hamas attacked Israel on 7 October, killing about 1,200 people and taking 251 others back to Gaza as hostages.