Independent broadcasters and newspapers in Poland have suspended their news coverage in protest over a planned new advertising tax.
At least 45 major media companies across the country joined the planned 24-hour demonstration on Wednesday.
Companies say the ruling conservative government is attempting to undermine press freedoms by imposing a tax on advertising income.
But the government says the draft proposals are intended to raise money after state finances have been badly strained during the COVID-19 pandemic.
Speaking to state television TVP on Tuesday, spokesman Piotr Mueller said the planned tax from advertising is destined for health and culture purposes and argued that similar policies exist in many European countries.
But Gazeta Wyborcza, the country's leading newspaper, called the advertising tax "a powerful blow to free media".
Like many others, the newspaper replaced its website with a black screen and written warning that if the advertising tax is passed, Polish readers could lose their independent news.
"On this page, you should see our content, [but] if the government's plans are successful, you may not really see it one day.
"You may also lose the opportunity to use other media and sources of information," the newspaper added, with the same message posted on Wednesday's paper front page.
The 24-hour news channel TVN, owned by US group Discovery, also joined the protest, saying the tax will lead to "the weakening or even liquidation of some media operating in Poland, which will considerably limit the ability of society to choose the content it is interested in."
Broadcasters also say the tax would favour the right-wing pro-government publishers, which are too small to be affected by the proportionate tax.
They wrote an open letter to Polish Prime Minister Mateusz Morawiecki saying the planned tax was "simply extortion".
TVP, which in recent years has been accused of airing propaganda of the ruling Law and Justice party (PiS), did not take part in Wednesday's blackout.
"I have no doubt that the aim is to hit the independent media," tweeted Adam Bodnar, Poland’s human rights ombudsman.
Media freedom in Poland and neighbouring Hungary has dramatically fallen in recent years, according to Reporters without Borders.
On Tuesday, a Hungarian court upheld a decision by media authorities not to extend a broadcasting licence to Klubradio, one the country's last independent broadcasters.