Wellington (AFP) - Hundreds of homes were evacuated in New Zealand Thursday after floods caused by torrential rains during a storm hit some parts of the South Island in the south of the island.

The tropical storm, which was accompanied by rainfall of up to 30 centimeters, caused rivers to overflow and trees fell, causing the closure of important road hubs.

On Wednesday, the authorities declared a state of emergency in Buller in the West Coast region and in the city of Nelson, where 233 homes were evacuated after a month's worth of rain fell in less than 15 hours.

Under the influence of these rains, the waters of the main river Matai in Nelson City overflowed, flooding homes and streets up to knee-high.

And the city's mayor, Rachel Reese, described these floods as "an event that is recorded once every hundred years," while search and rescue teams, in addition to elements of the army, were helping the people in the flooded streets.

Rais warned the people that the water should be treated as polluted, because some of the sewers had cracked.

For his part, Sam LaGrotta, a resident of Nelson who had to leave his house within five minutes, said the situation was "scary". "I picked up a handbag and threw my passport, my wallet and anything important I found in front of me," he told the New Zealand Herald newspaper on Thursday.

And 160 families have been asked to vacate their homes on the west coast of South Island.

Buller has experienced flooding several times in recent years.

The northern region, or North Island, was also affected, where three people were injured in a traffic accident when a tree fell.

Pooler Mayor Jimmy Klein said repeated evacuations have affected the town, which is now bracing for more flooding. He told the Stuff news website that the situation "causes people great trouble, financially and morally. This is our reality until a long-term solution is found."

Emergency Management Secretary Kieran McCann Elty visited Nelson on Thursday and promised financial help for the stricken town.

"The weather caused significant damage," he told reporters, adding, "While it is too early to know the full cost of the damage, this initial contribution of $200,000 ($125,460) will help ... provide immediate support to those who need it."