Turkey's supreme court has dealt a severe blow to the leader of the party tipped to win November's elections with a ruling which could stop him from standing.

The Ankara court on Monday re-instated the criminal record of Recep Tayyip Erdogan, leader of the Justice and Development Party (AK).

The ruling overturns a decision in a regional court last week which quashed his conviction for inciting religious hatred.

Turkey's election rules bar people with criminal records from standing for parliament. The country's election board is expected to make a final ruling on Mr Erdogan's candidacy in the next weeks.

Party confident

The AK party has been leading the opinion polls, with the latest survey putting it 10% ahead of its rivals.

As its leader, Mr Erdogan looked set to become the country's next prime minister.

Turkey's secular military has viewed the surge in the Islamist party's fortunes with suspicion.

Secular Turks are worried by the party's religious aspect

But the court ruling throws Mr Erdogan's and the party's chances into doubt.

Mr Erdogan spent four months in jail in 1998 after being found guilty of inciting racial hatred.

Last week, a court in the south-eastern town of Diyarbakir, overturned the conviction.

But despite the setback of Monday's ruling, Mr Erdogan's supporters are confident that the party will prevail.

"We believe that the (electoral board) will make the right decision and that we will enter the elections under our leader's direction," the party's deputy leader, Abdullah Gul, said.

There are more than 20 parties contesting the elections, which were called after Prime Minister Bulent Ecevit's government collapsed.

The AK party was expected to win up to half the parliament's seats.