Mozambique's military has been called in to help tackle severe flooding that has killed 48 people and is likely to spread to the country's central and northern regions, officials said Tuesday.

The armed forces have begun helping with clean-up operations in the devastated southern town of Chokwe, which has borne the brunt of the flooding caused by heavy rains.

"We can confirm the army is helping support the affected people," said Benjamim Chabualo, spokesperson for the Ministry of Defence told AFP.

Soldiers have also been involved in rescue efforts and the navy has ferried people by boat to reach areas isolated by flooding.

According to UN figures around 250,000 people have been affected by the floods and 146,000 people are being housed in temporary shelters.

Water levels have begun to recede in the south of the country, but the situation remains critical, and the centre and north are expected to be hit by fresh rain.

In Chokwe many homes have been completely inundated, and the flood surge has left in its wake piles of rubbish, mud and the detritus of lives destroyed.

"In Chokwe families have begun cleaning their homes and (the national civil protection unit) will help the municipality to clean the city," civil protection spokeswoman Rita Almeida said.

Even as the floods ebb in some places, residents faced a tough slog to get clean food, water, shelter and avoid a legion of risks.

"The rains over southern Mozambique have ceased for the time being, and the floodwaters are slowly receding. However, many have lost everything in the floods," according to a UN situation report.

At least 48 people have died, some electrocuted by severed power lines trailing in the water, some crushed by collapsed buildings and some attacked by crocodiles

At temporary shelters aid agencies are feeding approximately 70,000 people.

While tens of thousands of people have made their way to government camps, many more have not.

"We know there are a great many people affected who did not turn up at these centres," said Rita Almeida, Mozambique's national disaster management institute.

Some may have gone to the houses of family and friends, others, in more remote regions, remained stranded.

Helicopters are airlifting food and medical supplies to isolated areas.

"We are lifting supplies to places where neither boats or vehicles can enter," the Director-General of Mozambique's Disaster Management Institute (INGC) said on national radio.

"We are doing all in our power to get food to people where they need it."

The entire south and centre of the country is still on red alert for floods although authorities say water levels on main rivers are gradually dropping.

Authorities are monitoring the central Sofala and Zambezia provinces which have been registering rains.

"The forecast is it could keep raining for the next 48 hours and that the rain is moving north," Almeida said.

"We appeal to people to take precautions, particularly in houses made of material that is vulnerable to floods."

Some residents have refused to leave their homes out of fear of looting.

"If they stay on top of houses they can't benefit from aid. They prefer staying until the water goes down," Chokwe mayor, Jorge Macu�cua told AFP.