Hundreds of thousands of Burmese need urgent assistance
Britain has pledged another £12m to the Burma aid effort, bringing total government support to £17m.
The Department for International Development (Dfid) said £7m of the new money will go to the UN Flash Appeal, the rest to aid agencies.
Minister Douglas Alexander reiterated his call to the Burmese authorities to grant full and unfettered access for international assistance.
He said: "The lives of many hundreds of thousands of people are at stake."
"We know that people are lacking the basics such as clean drinking water, food and healthcare."
£4.6m already spent
He said that the additional £12m would allow humanitarian teams on the ground to continue to deliver emergency assistance.
"The key priority is to deliver humanitarian aid as quickly as possible. The clock is ticking," he said.
Mr Alexander said most of the £5m given last week had already been spent, with £4.6m used by aid agencies to provide drinking water, sanitation facilities, basic healthcare and shelter for more than 370,000 people.
DFID MONEY SPENT SO FAR
More than £1.1m to Save the Children to help 125,000 people in several towns in the Irrawaddy Delta
Up to £1m for Action Against Hunger to help 37,500 people in Bogale Township, Irrawaddy Delta
£700,000 for Care to help 60,000 people in towns near Rangoon
£500,000 for Medecins Sans Frontiers to help provide basic medical care, water and shelter for 100,000 people
More than £700,000 to Merlin to provide emergency healthcare for 50,000 in Laputta Township, Irrawaddy Delta
A total of £7m of the new money announced will be given to the UN Flash Appeal, which was launched on 9 May.
Of this, £5m will immediately go to the World Food Programme to provide logistical support for the relief operation.
Flash appeals raise cash to help the UN and its partners respond to natural disasters. A similar appeal was launched in January 2005 for the Asian tsunami late the previous month.
Two more Dfid-sponsored flights, carrying shelter and flat-bottomed boats, are due to arrive in Rangoon soon.
The Disaster Emergency Committee (DEC), an umbrella organisation for humanitarian aid agencies, said £6m of British aid had reached at least 350,000 people since the cyclone struck.
The junta, which is currently controlling distribution, has allowed the UN and some other agencies to hand out supplies directly.
However, it is still preventing foreign aid workers from entering cyclone-hit areas. Agencies are relying on their in-country and local partner organisations to distribute supplies.
Donations to the DEC Myanmar (Burma) Cyclone Appeal have now surpassed £6m. Chief executive Brendan Gormley said he could not stress enough the vital importance of individual donations from the public.
"Just a few pounds can provide essential shelter and aid to those left homeless by the cyclone.
"We'd like to thank the generosity people have shown so far and encourage people to continue donating so our agencies can keep up their life-saving work," he said.