International hackers's group says it took action following riot that took place on island's regional processing centre on Friday

The international hacktivist organisation Anonymous has claimed responsibility for bringing down the Nauruan government's website following a riot that took place on the island's regional processing centre on Friday evening.

A member of the organisation, who spoke to Guardian Australia, said the move followed another attack carried out by the group on the state's official internet provider, CenpacNet Inc, during the riot. This attack resulted in all official emails and government being shut down for over four hours. It was claimed that the Nauruan government had suspended all internet access outside of official use preceding the Anonymous attack. A spokeswoman for the Nauruan Information Office said it could not comment on the allegation.

Anonymous says the first attack was in direct response to calls from the Nauruan president for "strong and able men" to join police in preventing rioters escaping the regional processing centre.

The Information Office confirmed that the Nauruan chief of police, Richard Britten, an officer on secondment from the Australian federal police, was sacked during the riot for failing to contain the incident. He was replaced by a local senior officer named Kalinda Blake.

There are currently 150 asylum seekers, transferred from the Australian mainland for regional processing, charged by the Nauruan police over the riot, which saw the regional processing centre almost completely destroyed.

Joanna Olsson, the director of the Information Office, said that Nauru had enough correctional facilities to hold those charged following an expansion of cells on the island's jail. She added that those charged should be able to access Australian legal representation under the Nauruan constitution.

The Department of Immigration and Citizenship (Diac) confirmed that the remaining asylum seekers on the island, around 400, had been transferred to a second processing centre on the island, a flat "black soil site" with no permanent accommodation. It is understood that on Friday and Saturday night asylum seekers detained in this centre slept without any shelter. On Sunday night tent marquees had been installed, Diac confirmed. Guardian Australia understands there are currently no plans to transfer detainees from the island.

Diac's initial estimates suggest that Friday's riot caused $60m worth of damage. The department said it was conducting a fuller evaluation of the cost. Four asylum seekers were injured during the riot, Diac said, and 50-60 non-essential regional processing staff were returning to Australia following the incident.

It is understood that the riots followed peaceful protests earlier in the week against processing times for asylum claims. Guardian Australia also understands there were a small number of self-harm incidents during the week.