NAURU ISLAND, NAURU - JULY 20: (EDITORS NOTE: Best Quality Available) In this handout photo provided by the Australian Department of Immigration, workers extinguish flames after rioters caused AUD$60m damage on Friday evening, on July 20, 2013 on Nauru Island, Nauru. The riot came as news broke that the Australian government will send all asylum seekers to Papua New Guinea for processing and resettlement. (Photo by Department of Immigration via Getty Images)

Damage to the detention centre caused during the riot.

Charges against more than 20 asylum seekers over a riot at Nauru's detention centre last year have been withdrawn.

Nauru's newly installed Fijian magistrate Ropate Cabealawa was due to hear from 61 asylum seekers facing ''riot'' and ''unlawful assembly'' charges on his first sitting day of court on Tuesday.

The charges related to a riot at the Nauru Regional Processing Centre last year, which the Nauruan government says resulted in about $60 million worth of damage.

The government said in a statement that the magistrate adjourned the hearings in line with a request for an extension from a newly appointed prosecutor, in the wake of an upheaval in the nation's justice system.

Mr Cabealawa's six-month contract to replace ousted Australian Peter Law was announced on Monday night.

The Nauruan government sacked and deported Mr Law in January after he issued two injunctions restraining the government from deporting two residents without giving them any reason or right to challenge the action.

At the time, Mr Law was to preside over the trials of 85 asylum-seeker defendants. That month he was replaced by Melbourne lawyer Andrew Jacobson, who heard no cases and stood down all the cases for mention hearings.

A government spokeswoman confirmed that the charges of the remaining 24 were dropped earlier this year. She said that Mr Jacobson had left the island nation weeks after he was hired in January, as this was a temporary appointment.

More than 100 asylum seekers were initially charged after the riot.

''Some of the defendants who were not present [on Tuesday] were in Australia. However, the prosecutor informed the court that some of their charges had been withdrawn by application of a 'nolle prosequi' [do not prosecute] by the Director of Public Prosecutions, Wilisoni Kurisaqila,'' the government's statement said.

''His Honour was informed that the court's files had yet to be updated for that matter.''

The Nauruan government statement said that prosector Livai Sovau, who joined the Department of Public Prosecutions less than a month ago, had applied for an extension to serve ''the bundle of agreed documents … for the defence''.

The remaining defendants will next appear in court on March 18 and March 25 for mention hearings.

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