British counter-terrorism police have arrested four people in connection with a pro-Palestinian protest last week in which military planes were sprayed with paint at an air base in England, Reuters reports.

A woman, 29, and two men aged 36 and 24, were arrested on suspicion of the commission, preparation or instigation of acts of terrorism, while another woman, 41, was arrested on suspicion of assisting an offender, a police statement said.

Two activists from the Palestine Action group broke into the air base in Oxfordshire in central England on June 20, spraying red paint over two planes used for refuelling and transport, and further damaging them with crowbars, an act that was condemned by Prime Minister Keir Starmer as “disgraceful”.

Within days of the incident, interior minister Yvette Cooper set out plans to use anti-terrorism laws to ban Palestine Action, saying its actions had become more aggressive and caused millions of pounds of damage.

In response to Friday’s arrests, the campaign group accused authorities of “cracking down on non-violent protests which disrupt the flow of arms to Israel during its genocide in Palestine”.

Palestine Action has regularly targeted British sites connected to Israeli defence firm Elbit Systems and other companies in Britain linked to Israel since the start of the conflict in Gaza.