JOHANNESBURG, 4 January 2008 (IRIN) - As water levels continue to rise in Mozambique's main river systems, aid workers have expressed fears of a repeat of the 2007 flooding, the worst the country had experienced in six years.

"The water levels in four of the main river systems are way above the critical level," said Paulo Zucula, National Director for the Disaster Management Institute (INGC), told IRIN. The main river valleys Zambezi, Pungue, Buzi and Save - all in central Mozambique - which have already flooded and affected more than 50,000 people, have been put on red alert.

"We still need to rescue between 10,000 to 15,000 people from the affected areas," he added.

"Our other immediate concern is that the Cahora Bassa Dam [on the Zambezi River in the Tete Province in the northwest] has been forced to increase its discharges from 4,500 to 5,100 cubic metres a second to cope with a massive inflow of water into Cahora Bassa lake from Zambia and Zimbabwe," said Zucula.

Controlled releases from the Cahora Bassa dam which increase the flow downriver were partly responsible for the floods in 2007, in which 29 people were killed and 60,000 evacuated from the central Zambezi basin to higher ground.

Chris McIvor, country director of Save the Children UK pointed out, "With heavy rains forecast for Zambia, Zimbabwe and Malawi in the next few weeks - the situation could worsen [in the Cahora Bassa Dam]."