More than 13,500 people were being housed in evacuation centres following Cyclone Tomas, which battered Fiji's outer islands with winds up to 250kmh, flattening houses and causing sea surges, from Monday.
Fiji disaster management officials said they had received reports of "a few" deaths as the cyclone pounded the nation.
But National Disaster Management Office director Pajiliai Dobui said the numbers of dead and injured could not be confirmed by police until communications were restored with islands in the north and east.
Foreign Affairs Minister Murray McCully told Radio New Zealand a Hercules left New Zealand about 6am with relief supplies and personnel who would undertake reconnaissance work and damage assessment.
The plane may be in Fiji for several days and New Zealand would accept ongoing tasking if Fiji requested it, Mr McCully said.
"It appears that after the initial reconnaissance work's undertaken, damage assessment work, it'll be necessary to fly some supplies from Nadi or Suva to the affected areas, but quite how possible that's going to be is going to depend on the availability of suitable runways and that sort of consideration." An Orion was also on standby to provide further reconnaissance if required.
Mr McCully said Australia was making a similar offer of assistance and New Zealand's relief effort would be coordinated with Australia and France, "who've got assets in the area as well".
The Australian Government is sending up to $A1 million ($NZ1.26m) in emergency assistance to Fiji.
Australia will send a C130 Hercules -- loaded with tarpaulins, water purification tablets and containers -- as soon as the weather clears. It will be used for surveying damaged areas and carrying out medical evacuations.
Australia is also setting aside a commercial flight for use if it is required, following an official request for help from Fiji's interim government.
The $A1 million in funding will be directed to Fiji's National Disaster Management Office to help pay for charter transport such as helicopters and boats which deliver relief support.
The Fiji Red Cross will also get some money to assist in the distribution of emergency supplies.
"Last night I spoke to New Zealand Foreign Minister, Murray McCully, to discuss assistance to Fiji in the wake of the cyclone," Foreign Minister Stephen Smith said in a statement on Wednesday.
"Australia and New Zealand will work closely to co-ordinate our response.
"Australia will consider further assistance for reconstruction once damage has been more fully assessed." Hundreds of New Zealanders were known to be in Fiji but the Foreign Affairs Ministry said there had been no reports of any casualties.
At least five New Zealand tourists were trapped on the northeastern island of Qamea without phones and power, The Dominion Post reported.
A curfew placed on northern, eastern and central regions was lifted at dawn today, with a 30-day state of natural disaster declared in the northern and eastern areas.
The category four cyclone was expected to pass Fiji's southern-most island, Ono-i-Lau, by early today, and the nation's director of meteorology Rajendra Prasad said last night the hurricane force winds were likely to start weakening.
Disaster management team spokesman Laisania Tui told Radio New Zealand clearing up 34 schools used as evacuation centres was a priority, as well as clearing debris, providing clean water and avoiding an outbreak of disease, such as typhoid.
