BUDAPEST (Reuters) - Hungary’s leading internet news portal Index.hu, one of the last independent mass media outlets in the country, has been sold and its operations passed on to a foundation close to Prime Minister Viktor Orban’s one-time top ally and now his chief rival.

Hungarian Prime Minister Viktor Orban takes part in a European People Party (EPP) summit in St Julian's, Malta, March 30, 2017. REUTERS/Darrin Zammit Lupi

Index is by far the largest outlet to conduct investigations and break news critical of Orban after a major shake-up in Hungary’s media in recent years left most major news outlets under the control of the government or businessmen friendly with it.

With the transfer, Index joins a group of publications with ties to Lajos Simicska, one of Orban’s biggest political adversaries, a year before elections are due in April 2018.

Simicska, who was instrumental in building the current strong power of the populist Orban’s right-wing Fidesz party, fell out with the premier after the last elections in 2014 and broke with him in a profanity-laden public spat in 2015.

A magnate with positions in construction and agriculture who has recently expressed his preference for the radical nationalist Jobbik party, Simicska owns a sizeable media empire with daily Magyar Nemzet and news TV channel Hir TV.

Fidesz is the runaway leader in all polls attracting around a third of the electorate, far more popular than the top rivals, Jobbik and the Socialists, each with around 10 percent.

Index has dominated online media - something the new owner said it would try to preserve.

“100 percent of Index.hu has been transferred into a foundation on April 20 after Pro-Rata Holding, which also has stakes in Magyar Nemzet and Hir TV, exercised its options rights secured in February 2014,” Index.hu chief lawyer Laszlo Bodolai said in a statement.

“(Pro-Rata)...transferred its stake to (the) ‘For Hungarian Development Foundation’,” Bodolai said. The goal was “to preserve Index’s leading role in the market and its independence and to ensure its popular reach remains as wide as possible.”

Index’s new three-person board includes Ajtony Nagy, Simicska’s legal counsel who holds top positions in many of his largest companies.

Index was formerly the centerpiece of the media empire of banker and entrepreneur Zoltan Speder, once a key player in Orban’s plans to reform the bank sector, who also fell out of favor with Orban in 2016.

Reuters could not immediately reach Speder or Simicska for comment. The government spokesman declined to comment.