PRAGUE (Reuters) - Support for billionaire Andrej Babis’s ANO party dipped ahead of a Czech election on Oct. 20-21, but the party maintained a double-digit lead over its closest rival and remained favourite to lead the next government, an opinion poll showed on Monday.

Babis, the second richest Czech, has been harvesting disillusion of many voters in the central European EU member country with corruption in the political class, inefficient government and slow catch-up in incomes with the richer western Europe.

The final poll by the Median agency before a black-out starting on Tuesday showed eight parties winning seats, including a strengthening far-right, anti-EU formation.

Support for ANO dipped to 25 percent in the survey conducted on Sept 26-Oct 14, down from 27 percent in September.

ANO has maintained it image as a protest party despite serving in the outgoing cabinet as partner to the centre-left Social Democrats of Prime Minister Bohuslav Sobotka.

Babis’s image suffered from police charges earlier this month of fraud in tapping European Union subsidy, a small project among many by the chemicals, food and media businessman worth $4 billion according to Forbes magazine. He denies any wrongdoing.

A Slovak court also annulled last Thursday rulings clearing Babis of cooperating with former Communist secret police in then totalitarian Czechoslovakia. He denies being an agent.

The poll showed ANO will need partners to form a parliamentary majority. A relatively weak showing by ANO would embolden potential partners demanding that Babis personally stays out of the cabinet due to the police charges.

Babis served as finance minister from 2014 until May this year, presiding over a drive to raise tax collection and a fiscal surplus last year.

He opposes deeper EU integration and adopting the euro. He also opposes accepting any refugees.

Rivals say he poses a threat to democracy due to his authoritarian style, desire to simplify decision making, and conflicts of interest as businessman whose firms compete for state contracts and receive subsidies.

Babis moved his firm Agrofert to a trust fund earlier this year and denies any abuse of his position.

The Social Democrats -- who have not ruled out a new coalition with ANO -- polled second with 12.5 percent, down 1 percentage point, followed by the far-left Communists with 10.5 percent.

PROTEST VOTE

The rise of ANO and other protest groups show a shift from traditional parties even as the country enjoys fast economic growth and the lowest unemployment in the EU.

The Social Democrats lost about 40 percent of voters and the centre-right TOP 09 party polled 6 percent, half of its score in the previous election.

The far-right, anti-EU SPD party jumped to 9.5 percent, tapping into anti-immigration sentiment in a country that saw almost none of the 2015 immigration wave into Europe.

The Pirate Party, a local offshoot of the international Pirate movement which focuses on government transparency and an electronic agenda polled 8.5 percent, giving it chances of entering parliament for the first time.