There are unconfirmed reports of deaths in Fiji, as Cyclone Tomas moves through the northern part of the island group.

At least 5,000 people are sheltering in evacuation centres ahead of the main force of the cyclone, which is expected to pass close to the capital Suva tomorrow morning.

Disaster Management official Anthony Blake says trees are down, power is out in some areas and there are reports of damage to houses and a kindergarten on one of the islands in the far north of the country. Officials are trying to verify the reports of injuries and fatalities.

Weather analyst Philip Duncan from WeatherWatch.co.nz, says Tomas is an aggressive storm with its strongest winds gusting up to 250km/h. He says it will start to move across the two main Fijian islands starting in the east this afternoon and spread west during the night.

"Tomas is moving very slowly which significantly increases the potential for serious flooding and wind damage."

New Zealander Laura Noblejas is holidaying near Nadi and says tourists are on alert.

"We've been told to pack our suitcases and be prepared to evacuate from our waterfront hotel tonight, most likely between 6 and 9pm."

Ms Noblejas says many shops and banks have closed and smaller businesses have moved stock to higher shelves in case of flooding.

"Some buildings have cyclone shutters and wooden boards up over windows."

Another tropical cyclone which is also menacing the Pacific region is now heading into the open waters of the Coral Sea after causing less damage than expected to the Solomon Islands.

Tropical Cyclone Ului is currently a category four storm and Mr Duncan says while it is a smaller cyclone than Tomas, it will be far more intense.

"A bit like a figure skater pulling its arms in, Ului will spin faster and cover less area."

Cyclone Ului is predicted to become an intense category five cyclone by midnight tonight with winds gusting up to 350km/h. Computer models show it will brush the Queensland coast causing what Mr Duncan describes as phenomenal seas. Its current estimated time of arrival in Australia is this weekend. WeatherWatch.co.nz predicts that northern New Zealand will potentially be in the firing line around Wednesday next week but adds it is still too early to know what impact it could have.