Geneva, May 16 (DPA) The Red Cross launched an emergency appeal Friday for $50.8 million for Myanmar following Cyclone Nargis.

'The cyclone was a monumental disaster and we are now facing a humanitarian catastrophe of staggering proportions,' International Federation of the Red Cross and Red Crescent Societies (IFRC) secretary general Markku Niskala said.

The appeal aims to help 500,000 people in the disaster-struck delta zone with basic shelter and water for three years.

The Red Cross said it was extremely concerned about the prospect of further heavy rains in the coming days and the possible health risks as well as the threat they posed to the already difficult job of distributing aid.

The limited airport and truck capacity were two bottlenecks hampering the aid operation.

IFRC said a further five flights were due to land in Myanmar Friday, bringing to 21 the total number of aid flights by the organization.

By the end of the weekend, 240 tonnes of aid should have arrived in the country.

'Assistance into the country is gaining momentum but more needs to be done. It is clear greater access is needed if you are to ensure aid is delivered effectively to the most vulnerable people,' Niskala said.

Around 500 Red Cross emergency shelter kits were distributed Thursday with another 600-700 scheduled for distribution Friday. There were 18,000 more waiting in warehouses, but distribution was difficult as they had to be airlifted in due to the weight.

The Red Cross has reached around 100,000 people so far and said UN figures that around a third of those in need had received some form of help were the most accurate available.

The organization said it was considering launching a seaborne operation with floating warehouses to counter the ongoing logistical difficulties that would be further hampered by heavy rain, such as was set up following the December 2004 Asian tsunami.