A senior government official said more than 2,600 people were sheltering in evacuation centres. File photo/AFP

Tropical Cyclone Tino strengthened to a Category Two storm on Saturday and was heading towards Tonga after battering Fiji where two people were missing and more than 2,000 fled to emergency shelters.

The Fiji Meteorological Service said the wind gusts from Tino had increased to 155 kilometres per hour (96 miles per hour) and the danger of "destructive storm-force winds" and flooding remained.

Uraia Rainima, a senior government official in the northern region of Fiji, said more than 2,600 people were sheltering in evacuation centres.

Their houses were being checked on Saturday before they could return home, but Rainima believed damage was not as great as first feared.

"We will confirm if there is any damage to their dwellings, but we know for sure most of them went to the ECs (evacuation centres) to take shelter because of the big rains we were receiving and also because of the warnings," he said.

The island of Taveuni, with a population of around 19,000 people, was without power, Rainima said.

Police, meanwhile, continued the search for a father and his daughter who were swept away when they tried to cross a swollen river on Thursday evening.

Tonga was calm Saturday with light winds and little rain ahead of the approaching storm which was expected to hit overnight.