Silvio Berlusconi, Italy's prime minister, has blown apart a deal between the two biggest parties in the European Parliament over sharing the presidency of the assembly for the next five years.

His intervention has put in doubt the assumption that the presidency would go next to an MEP from one of the countries that joined the European Union in 2004.

The centre-right European People's Party-European Democrats (EPP-ED) and the Party of European Socialists (PES) had privately agreed that over the Parliament's next five-year mandate the presidency would be shared. Jerzy Buzek, a former prime minister of Poland and an EPP-ED MEP, would be president for two-and-a-half years, followed by Martin Schulz, a German Socialist MEP who is currently leader of the Socialist group in the Parliament.

But Berlusconi has thrown the deal into confusion, announcing in a letter sent to national delegations of the EPP-ED group that Mario Mauro, an MEP since 1999, is his candidate for the presidency of the Parliament.