A referendum on the single currency could come as early as this autumn or next spring, the Europe minister Peter Hain has hinted.

In comments which fuel speculation about an early poll, he said that the government's assessment of the five economic tests would be completed by the autumn.

Hain, speaking in an interview with Paris-based "Le Figaro" newspaper, said that Britain could join the euro within two years of a successful referendum.

In a move which will increase government splits on the single currency, Hain said that the "enemies of the euro are the enemies of Europe".