Prime Minister Tony Blair was forced to delay a speech to business leaders in north London today, after a protest by anti-nuclear demonstrators.

The Prime Minister was to appear at the Confederation of British Industry's annual conference, and organisers hurriedly moved his speech on energy policy to a nearby hall.

Greenpeace said two people had climbed into the ceiling above the speaker's podium at the Business Design Centre in Islington.

The climbers then unfurled a banner marked "nuclear - wrong answer" and dropped what the group said was "radioactive" confetti to prevent the PM from speaking.

Stephen Tindale, Director of Greenpeace UK, said the organisation was determined to stop any plans for more nuclear power stations.

"Nuclear power is not the answer to climate change - it's costly, dangerous and a terrorist target."

Mr Blair is expected to announce a long-awaited review of energy policy, with speculation this could include plans for more nuclear power.

In notes released beforehand, Mr Blair said rising energy prices had combined with supply problems and climate change to produce a sense of urgency.

"Round the world you can hear the heavy sound of feverish rethinking," the PM was to say.