More tear gas was used by Australian Federal Police against detainees on Christmas Island last night, as asylum seekers continue to protest against conditions on the island and the length of time taken to process claims.

The AFP has confirmed Operational Response Group members were forced to use tear gas on detainees at North West Point detention centre around 8pm last night after a protest got out of hand. According to the Department of Immigration and Citizenship, around 250 detainees were involved in the protest. Fires were also lit, but they were small and contained within wheelie bins, a spokesperson said.

According to the AFP, protesters ignored repeated warnings from the AFP and advanced on them with “impoverished weapons”, including rocks. During the incident some staff of Serco, managers of the centre, and vulnerable detainees took refuge in the front reception of the detention centre.

Immigration Minister Chris Bowen told ABC Radio in Perth this morning that an increasing number of rejection rates was going to lead to more protests.

“Clearly we need to reduce the numbers on Christmas Island … as a response to this issue,” he said. “Numbers on Christmas Island are high. I’ve taken steps to reduce numbers.”

Bowen also said there were “well over 80” AFP officers stationed on the island, who would stay “for as long as they are required”.

The latest response comes after around 200 detainees broke out of the detention centre on Saturday and Sunday to hold a protest at the Christmas Island airport. AFP members used tear gas and less lethal munitions — also known as “bean bag” rounds — to quell the protest after it began to turn violent. Last night’s incident marks the latest in a string of protests at the centre, Bowen has called an “orchestrated campaign”.

According to an AFP spokesperson, the use of tear gas last night was in accordance with the provisions of Commissioners Orders on Use of Force. They did not say whether bean bag bullets had been used on the protesters.

Bowen has said Sunday’s initial violence was triggered when security officers handcuffed 10 accused ringleaders of the breakout. But refugee advocates have also raised issues with Serco’s actions during the initial protests, including the use of detention centre staff — chefs and kitchen hands, among others — to provide a “show of force” during the initial disturbance.

DIAC told Crikey to speak to Serco about the claims, while Serco advised it was more appropriate to speak to DIAC. And a spokesperson for the minister’s office denied the claims.

Concerns have also been raised about the protesters on Christmas Island and their access to services, including legal advice. Bowen has already said the visa claims of protests will be delayed.

An independent “arm’s length” inquiry will be held into the handling of the Christmas Island incident. According to DIAC, the AFP’s use of force will be investigated, as will Serco and DIAC’s response. It’s still unclear as to who will be holding the investigation and how it would remain independent. A spokesperson for DIAC told Crikey details of the inquiry would be relased “in due course”.

On Wednesday, a group of Rohingyan asylum seekers were protesting on the roof of a building at Darwin’s northern immigration detention centre. Refugee advocates say the protest ended when DIAC flagged an inquiry into the actions of two security guards. DIAC has confirmed to Crikey there was another disturbance overnight at the Asti Motel in Darwin, where around 20 residents protested in the carpark.