George W Bush has offered $770m (£390m) in international food aid to help ease the effects of surging food prices that have sparked riots in some countries.

The US president said he was asking Congress to approve his request.

The White House has come under intense pressure to step in as high food and petrol prices have squeezed poor families both at home and abroad.

The global crisis has sparked rioting in several developing countries, with the threat of worse to come.

"We're sending a clear message to the world that America will lead the fight against hunger for years to come," said Mr Bush.

'Silent tsunami'

The new money would come in addition to some $200m the US president released for emergency food aid two weeks ago, but Mr Bush warned that "more needs to be done".

"In some of the world's poorest nations, rising prices can mean the difference between getting a daily meal and going without food," he said.

"The American people are generous people and compassionate people. We believe in the timeless truth, to whom much is given, much is expected."

Food price increases, dubbed by the United Nations World Food Programme a "silent tsunami", have sparked riots in some countries, including Haiti, Cameroon and Indonesia.

The UN has warned that high prices are expected to continue despite increased production.