As many as one million people rallied in a sea of red Turkish flags in Istanbul yesterday, accusing the government of planning an Islamist state and demanding it withdraw its presidential candidate.

Despite the protests and a threat from the powerful army to intervene in the election, Foreign Minister Abdullah Gul, architect of Turkey's EU membership drive, said he would remain the ruling AK Party's candidate for head of state.

The protesters flooded the streets of Turkey's largest city, praising the army and denouncing Mr Gul and Prime Minister Tayyip Erdogan, whose AK Party enjoys a huge parliamentary majority, as a threat to a secular order separating state and religion.

"Turkey is secular and will remain secular," and "government resign," they chanted.

The AK Party faces its biggest crisis since it was elected in 2002. Parliament elects the president, who carries great symbolic weight and has important veto and appointment powers.

"We are here to stop the creation of an Islamic state," said businessman Irfan Kadim, 35. "We fear for the secular republic."

Many secularists are worried by Mr Gul's Islamist past and the fact his wife wears the Muslim headscarf banned in universities and public offices.

The AK Party, which has vigorously pressed liberal reforms and overseen strong economic growth, denies any Islamist agenda.

The protests wound down by early evening. One police official said more than 750,000 attended, while CNN Turk said the district town hall put attendance at 1.2 million.

Many analysts say the only way to diffuse the crisis would be to call early general elections, scheduled for November. Turkey's top business association, Tusiad, backed a call for early elections, which opinion polls showed the AK Party would be well placed to win. Secularists hope a newly elected parliament would chose a consensus president.