Ibon Villelabeitia: Turkish PM set for major gains from scandal -hit rivals

The scandal has thrown the far-right Nationalist Movement Party (MHP) into disarray. Ten senior members caught by peephole cameras have resigned in the wake of the scandal, which has also prompted speculation over who may be behind the "dirty politics".

"There is no doubt this is a slick, carefully planned smear campaign," Wolfango Piccoli, of the Eurasia risk consultancy, said. "I don't think we have seen this type of technique during elections in Turkey in the past."

A distant third place behind Mr Erdogan's AK party and the main opposition People's Republican party (CHP), the MHP's chances of notching up 10 per cent of the vote - the threshold needed for a party to take seats in parliament - have been dented. If the MHP can't take up its seats, they will be carved up by the other parties on a proportional basis - and the party that stands to gain the most is Mr Erdogan's AK.

Opinion polls already show the AK garnering between 45 per cent and 49 per cent of the vote in the 550-seat assembly. If, thanks to the MHP's convulsions, the AK ends up with a two-thirds majority it will have the power to pass constitutional reforms.

Mr Erdogan wants to replace a charter drafted after a 1980 coup with one that is more pluralistic and democratic, fulfilling a long-standing requirement to meet European Union standards.

Some critics accuse the AK of harbouring Islamist tendencies and fear a new charter will water down Turkey's secularist principles.

A reformist party which has its roots in banned Islamist movements, the AK has increasingly taken the space of the MHP with a more nationalist message, analysts say.

The edited videos are not explicit - for example showing couples putting their clothes on without showing what went on before - but they also record MHP men making politically compromising remarks.

The videos were posted on a website called "Different Idealism", an allusion to the "Idealist" movement which forms the backbone of MHP support.

The site had threatened to post the videos if party leader Devlet Bahceli did not step down by a deadline of 18 May.He did not resign.

The little-known website has now been blocked while an investigation takes place, but experts say the footage was the product of a professional surveillance job.

The episode has fed a paranoia already rampant in this Muslim democracy.

Many Turks believe their private conversations are routinely wire-tapped by police and that secret camera footage has become a weapon between warring political camps.

The "Ergenekon" investigations into alleged plots by clandestine groups to topple Mr Erdogan's government - first hailed as an opportunity to clean up Turkey's dirty past - have created a perception among Turks that "Big Brother" is lurking and that systematic violations of privacy have become normal.

Deniz Baykal, the veteran CHP leader, resigned last year after a videotape posted online showed him in a bedroom with a woman from his party who was not his wife.

Mr Erdogan has denied allegations his party played a role in the latest scandal and described the campaign as "dirty and dangerous".

In a country where there is no shortage of conspiracy theories, fingers are pointing in all directions. A foreign intelligence agency has been blamed, as well as Turkish exiles and a disgruntled MHP faction. One MHP official even suggested that US president Barack Obama had played a role.

The MHP, which considers itself the guardian of Turkishness and family values, has struggled to remain relevant as European Union candidate Turkey has become more democratic and open.

Its fiery leader, Mr Bahceli, has made a career out of resisting human rights reforms and Kurdish rights which are meant to level Turkey's path to the EU, calling for the return of the death penalty and of restrictions of house sales and land to foreigners.

Ultra-nationalism often turns violent in Turkey, and the MHP's "grey wolf" followers were very active in left-right street battles in the 1970s.