New Zealand police said on Thursday they had levelled five murder charges against a man suspected of igniting a deadly hostel fire in Wellington last month.

The 48-year-old, already remanded in custody on two counts of arson, now also faces five murder charges, police said.

The blaze engulfed the four-storey, 92-room Loafers Lodge hostel a fortnight ago in Wellington's city centre, killing five men whom police have named.

Inspector Dion Bennett, acting Wellington district commander, said the victims' families have been informed. "Our thoughts are with them and we are continuing to ensure they are supported through this process," he added.

The suspect, who cannot be named under an interim court suppression order, appeared in court on May 19 after being charged with starting a sofa fire inside the hostel and, a few hours later, setting the building itself alight.

He did not make a formal plea.

Due to extensive fire damage inside the hostel, police said it took two weeks to examine the building.

A dawn "karakia" – a Maori ceremony – will take place at the hostel on Friday morning for police staff involved in that operation, Bennett said.

The scale of the fire shocked the country, with Prime Minister Chris Hipkins describing it at the time as an "absolute tragedy" while promising a thorough investigation.

Some survivors crawled through smoke in the dark of night to escape the fire, while others were rescued from the rooftop by firefighters. (AFP)