A cargo plane carrying 35 tonnes of emergency aid left an airport in southwest France on Saturday heading for the victims of Cyclone Nargis in Myanmar.

The chartered Il-76 freighter, originally due to leave on Friday, mainly carried shelters, water-treatment equipment, first-aid supplies and specialist foodstuffs, said Bruno Delouche of French charity Doctors Without Borders (MSF).

A second plane, an Airbus A300, combining aid from MSF and the French Red Cross, was also due to leave Bordeaux-Merignac airport on Saturday morning, but remained grounded owing to flyover restrictions applied by unnamed countries, a Red Cross official added.

The second load amounted to another 36 tonnes of materials, 14 of which have been assembled by the Red Cross.

The supplies left France as the UN food agency said Myanmar's junta had released a plane-load of cyclone aid into its custody Saturday.

The junta, deeply suspicious of the outside world, has refused to let in foreign experts who specialise in getting aid to disaster victims, and said that only the government would be allowed to distribute emergency supplies.

The cyclone, which slammed into the rice-growing Irrawaddy Delta region in the country's south, left 60,000 people dead or missing and as many as two million more short of food, water and supplies.

The MSF contribution includes "20,000 emergency kits," which enable medics to treat malaria or give tetanus infections, as well as "tents, mosquito nets and power generators".

The aid group aims to set up several distribution centres and medical access points, said logistics expert Fabio Baccan, who left with the plane.

The grounded Red Cross shipment, meanwhile, includes materials for the construction of a water purification station capable of producing 600,000 litres (1.3 million pints) of drinking water per day.

A second joint load, uniting the two charities, was also due to leave from Vatry airport in northern France on Monday.

MSF said that a separate plane carrying 40 tonnes of equipment would also leave Belgium on Sunday, after having obtained landing authorisation from Yangon.

"Some opening-up on the part of the (Myanmar) authorities is allowing us to get these materials to their destination," said Stephan Goetghebuer, MSF director of operations, in a statement.

"But it's no more than a drip-feed, really, given a serious response is more than required. We still need more back-up aid and personnel ready to leave," he added.

MSF's network is working overtime to have shipments ready as and when they receive green lights, with another plane also on standby in Jakarta for the coming days.

The international community has spoken out in increasingly concerned tones over Yangon's apparent sluggishness or suspicion when it comes to taking up offers of overseas, even non-governmental aid.

Both French President Nicolas Sarkozy and German Chancellor Angela Merkel spoke on Saturday of their dismay at Myanmar's stance, with each having pressed the United Nations Security Council to intervene.

The UN has itself said that a week after Cyclone Nargis hit, only one-quarter of the victims have received any help at all, and it has called the relief effort "a race against time."