The government will veto any version of the proposed European Union constitution which could weaken Britain's ability to resist majority voting in key areas such as taxes and defence, Jack Straw warned yesterday.

With the Thessalonikki summit marking the end of the six-month Greek presidency beginning later today, Tony Blair and the French president Jacques Chirac joined forces over poverty and disease in Africa.

The two leaders wrote to Costas Simitis, the Greek prime minister, calling on the summit to match the US commitment of £600 million to the Global Health Fund next year to tackle HIV/Aids, TB and malaria.

Writing in the Mirror, Tony Blair says Iain Duncan Smith makes Margaret Thatcher look like a "euro fanatic" by comparison.