Gordon Brown has predicted a fall in oil prices after a global summit in Saudi Arabia.

The Prime Minister refused to make any promises about the level prices will reach at the pump but said an agreement had been reached with members of the Opec cartel.

The oil producers accepted that record prices of almost $140 a barrel were causing damage and investment was needed to increase supply.

Mr Brown said: "What we have got is an agreement here - perhaps for the first time - that the oil price is too high and it is detrimental, it is causing damage and that there must be more investment in the supply of oil immediately and for future years.

"What we've also got is an understanding that we've got to diversify out of oil and we've got to back nuclear, we've got to back renewables."

Mr Brown offered to open Britain's energy markets to oil-rich states, urging them to reinvest some of the $3 trillion of additional revenue from soaring oil prices into wind and solar energy and a new wave of nuclear power stations.

He said Britain had entered into commitments with Saudi Arabia to develop environment-friendly carbon capture and storage technology; with Qatar to explore the possibility of a new joint energy fund; and with the United Arab Emirates to work on opportunities in nuclear energy.

A decision on £800 million of Norwegian investment in the Scira wind farm project off the British coast is expected soon.

Mr Brown told the conference the world is going through "the third great oil shock in as many decades" which is having a "severe impact" on standards of living around the globe.

He called for a "new deal" for global energy, building "a greater commonality of interest between producers and consumers".

And he quoted predictions that the world will need 1,000 new nuclear power stations, 700,000 new large wind turbines and a 600 per cent increase in energy from solar, biomass and hydro-power sources by 2050.

He told the summit: "I propose that Britain and other oil consumers should open up our markets to new investment from oil producers, including sovereign wealth funds, in all forms of energy including renewables and nuclear - providing oil producers with a long-term future in non-oil energy."

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