The unprecedented Tasman bush fire remains uncontained and flared up again overnight, reminding firefighters that it is "still the boss".

As the battle to contain the massive blaze enters its eighth day, fire officials said this morning that it sparked up again around midnight.

The fire breached control lines near Eves Valley but was quickly dealt with by fire crews on the ground who had been positioned downwind.

"For us, it's the fire telling us it's still the boss," said Fire and Emergency New Zealand fire controller Trevor Mitchell today.

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The fire is still not contained, he said, leaving firefighters with "quite a lot of work to do".

Updated data shows the fire is now spread across 2400 hectares, with a perimeter being reassessed at 33km.

Mitchell said that the female firefighter hospitalised yesterday with dehydration was recovering well.

Tasman Mayor Richard Kempthorne reminded locals that they face a long recovery.

Firefighting efforts on the ground will be ongoing for "at least a month, mostly likely longer", he said.

Hi everyone, if you have been affected by the fire and need assistance please come and visit our Richmond Civil Defence...

Posted by Nelson Tasman Civil Defence on Tuesday, 12 February 2019

Authorities are today still working on plans to assess when evacuated residents of the areas known as the valleys can go back home.

It was a complex task, with about 200 properties involved, Civil Defence controller Roger Ball said.

There is no timeframe yet but there will be a community meeting tonight at 7pm in Hope, where the valleys re-entry will be the top of the agenda.

Meanwhile, police investigations into the suspicious and unrelated Rabbit Island and Nelson city fires are continuing.

Acting Tasman district commander Inspector Zane Hooper said staff were actively following up inquiries.

Hooper said there have been no reports of looting, but reminded people to stay away from cordons.