A family of four, including two children, were killed in a landslide late Wednesday after becoming trapped in their home at a village in the island's western Ba region, the information ministry said.

It said almost 3,500 people had been forced from their homes by the torrential downpour that has continued since the weekend, and a state of natural disaster has been declared in the worst-hit areas of the west.

No further details of the landslide victims were available.

Earlier this week, two farmers were killed in separate incidents as they tried to protect their livestock from rising waters.

The government said roads had been cut and some communities were without power and water supplies, advising people to avoid low-lying areas and take precautions against water-borne illnesses.

New Zealand Foreign Minister Murray McCully announced an initial NZ$350,000 ($286,000) for flood-relief efforts and said further aid was being considered.

"New Zealand is coordinating closely with authorities and relief agencies on the ground, as well as with Australia and France," he said.

Army helicopters and motorboats were deployed to the southern district of Nsanje, along the Mozambican border, to rescue marooned villagers.

Nsanje has been "receiving heavy rains since mid-last week which has resulted in two big rivers to break their banks and flood scores of villages," district commissioner Rodney Simwaka told AFP by telephone.

The Shire River, which flows out of Lake Malawi, and the Ruo, which originates from the picturesque Mulanje Mountain, have flooded following heavy rains caused by Cyclone Funso, a powerful Category 4 storm moving slowly through the Mozambican Channel.

Simwaka said about 2,500 villagers fled to hills when the floods hit homes along the rivers.

"Several thousands of people are still marooned in dry patches of land in the flooded villages," he said.

Roads and bridges leading to Nsanje, 175 kilometres (110 miles) from the commercial capital Blantyre, had been washed away, cutting off 30 villages.

He said the helicopter and engine boat operation to rescue the villagers started on Tuesday. Only 99 villagers have been flown to safety and were being housed in schools and churches where the government was distributing food and relief items.

No deaths were reported, but hundreds of hectares of the maize fields were under water and scores of cattle, goats and chickens had been washed away, he added.

The district is prone to floods every year and thousands of villagers defy government orders to move to higher land because they want to grow crops in river banks after the floods, which leave soil rich in silt.