Dozens of journalists walked out of Hungary's top independent news site on Friday in protest at the removal of its editor-in-chief, with some warning the events marked the "destruction" of yet another pillar of press freedom.

Index.hu is Hungary's most-read news portal and a rare independent voice in a media landscape increasingly controlled by allies of Prime Minister Viktor Orban.

On Wednesday, its editor-in-chief Szabolcs Dull was fired, with management claiming he had leaked internal documents to other media.

That prompted three senior editors to resign on Friday, followed by more than 80 journalists -- the overwhelming majority of the newsroom.

In a statement, the site's journalists condemned Dull's dismissal as "an overt attempt to apply pressure on Index".

Miklos Hargitai, president of the Hungarian journalists' association, said that the events meant "another dominant Hungarian institution is in the process of being dismantled, occupied and destroyed by (Orban's right-wing) Fidesz" party.

Index tweeted photos of distraught journalists in tears and hugging each other as the resignations were announced.

On Friday evening around 3,000 protesters turned out in central Budapest to express their support for the journalists.

Index has roughly two million readers per day in a country of just under 10 million.

Dull himself warned last month that the site was in "grave danger" from a proposed organisational overhaul.

That followed a purchase of 50 percent of Index's advertising agency by powerful pro-Orban businessman Miklos Vaszily in March.

In recent years most independent outlets have either gone out of business, or been bought by government allies while receiving lucrative flows of state advertising.

Public media has meanwhile been turned into a government propaganda organ.

International observers say a lopsided media landscape and restricted access to information helped Orban win a third consecutive term as premier in 2018.

Protesters hold a banner with the slogan "Free country, free press" after the editor of an independent news site was sacked prompting a mass staff walk out
Protesters hold a banner with the slogan "Free country, free press" after the editor of an independent news site was sacked prompting a mass staff walk out AFP / ATTILA KISBENEDEK

Hungary's embattled opposition parties lined up to denounce what has happened at Index.

"A flame has gone out, but we will not forget who was responsible," said Andras Fekete-Gyor, president of the liberal Momentum party.

The liberal mayor of the capital Budapest, Gergely Karacsony, posted a message on Facebook in which he paid tribute to the "courage" of the Index journalists in "standing up for our principles as a community".

However, on Thursday Foreign Minister Peter Szijjarto denied the charge that the government had anything to do with Dull's sacking.

"Do you think the state should intervene in the decisions of a private body?" he said to reporters on a trip to Portugal.

"In Hungary this would be unacceptable," he added.

Government critics nevertheless see what is happening at Index as the continuation of a long chain of events which has seen the media align ever more closely to Orban's government.

They fear a repeat of what happened to another prominent news website, Origo, whose editor was sacked in 2014.

That also prompted a mass walkout by staff who suspected political interference and the site was then sold to a media firm linked to Fidesz.

Origo's content openly lurched towards a pro-government line with the arrival of a new editorial team in 2016.

Also in 2016, the left-leaning Nepszabadsag newspaper suddenly ceased operation before its publisher was snapped up by oligarch and close Orban ally Lorinc Meszaros.

Two years later, ownership of ten publishers comprising an estimated 500 media outlets were transferred to a holding company headed by a loyal ally of Orban.

The company's stated aim is to develop "public discourse based on national values".

The narrowing of Hungary's media landscape is one aspect of the centralisation of power which has lead to clashes between Orban's government and the EU.

On Thursday Index published a letter from European Commission Vice-President Vera Jourova in which she said she had been "following the situation of Index with concern".

She expressed her "solidarity" with Index staff and told them: "You can count on my support."

Earlier this week Hungary and Poland, both countries in the EU's sights for alleged breaches of norms on judicial independence and media freedom, fought hard to water down provisions in the EU's coronavirus recovery programme which would link spending to respect for the rule of law.