Rached Ghannouchi, whose Islamist movement Ennahda is considered Tunisia's most popular party, pleaded on Tuesday for the country's first post-revolution elections in October to be transparent.

"The most important thing in our view is that the elections be clean. Some players still refuse to recognise our legitimacy," Ghannouchi told AFP in an interview.

The north African country is set to elect a constituent assembly tasked with drafting a new constitution in October 23 polls, the country's first elections since the January toppling of long-time dictator Zine el Abidine Ben Ali.

Some of Ghannouchi's adversaries have raised questions over Ennahda's financing, accusing the Islamist movement of receiving large amounts of money from Gulf countries.

Ghannouchi returned from 20 years of British exile in January, in the immediate aftermath of Ben Ali's shock departure under pressure from the street, and his party was legalised on March 1.

Echoing fears expressed by many Tunisians since the collapse of the Ben Ali regime tipped the first domino of an "Arab Spring" still sweeping the region, Ghannouchi warned that the uprising's achievements could yet be rolled back.

"Everything is possible in Tunisia. The losers and anti-revolutionary forces are capable of anything to thwart the will of the people," he said.

"Our score is of little import," Ghannouchi said, sitting in his office in the brand new headquarters of the Ennahda (Renaissance) party in Tunis' modern Montplaisir neighbourhood.

"What matters is that we get a transparent and democratic vote. These will be the first free elections in the history of Tunisia," he said.

With 20 percent of voter intention, Ennahda leads the field in opinion polls.

"We hope to achieve more than that," Ghannouchi said, claiming that his movement has around one million supporters and is the country's best-organised.

"Our priorities are the fight against unemployment and corruption," he said, without going into the details of Ennahda's campaign programme.

Tunisia's revolt started in December with protests against unemployment and the rising cost of basic goods.

"We want the establishment of a parliamentary regime which guarantees a strong representation for the regions in order to obviate any authoritarian relapse," said Ghannouchi, whose party was fiercely repressed under Ben Ali's 23-year rule.

When asked about fears in Tunisia's secular and intellectual circles about Ennahda's religious doctrine, Ghannouchi stressed his commitment to democracy and vowed not to undermine the status of Tunisian women, often considered one of the best in the Arab world.

"The code of personal status (Tunisia's groundbreaking 1950s series of laws enshrining the equality of men and women, abolishing polygamy and allowing divorce) and women's rights cannot be touched.

"Women make up half of society and we need their votes," he said.

Ennahda has complied with the law requiring parity on the 33 electoral lists it presented for next month's elections, although only two are headed by women.