Donald Trump has attacked the escalating investigations into 3,000 adverts purchased on Facebook by Russians in the 2016 US presidential, using Twitter early Friday to say the “Russia hoax continues, now it’s ads on Facebook”.

He repeated his attacks on the “biased and dishonest” media coverage that he said favored his rival Hillary Clinton.

The US president made the comments a day after Facebook said it would provide congressional investigators with the contents of those adverts, following weeks of scrutiny surrounding the social network’s role in influencing elections.

There is growing pressure for such digital platforms and Google to have tighter oversight on political adverts more akin to regulations on TV and other media.

Facebook CEO Mark Zuckerberg broke his silence on the issue in a Facebook live video on Thursday, saying that the company would provide the controversial ads to government officials to support investigations in the US and as part of its renewed efforts to protect the “integrity” of elections around the world.

“I don’t want anyone to use our tools to undermine democracy. That’s not what we stand for,” he said. “I wish I could tell you we’re going to be able to stop all interference, but that just wouldn’t be realistic,” Zuckerberg added. “There will always be bad actors.”

US congressional investigators and special counsel Robert Mueller are examining alleged Russian election interference, which Moscow has denied.

Trump has regularly characterized as a “hoax”and “witch hunt” anything linking his election campaign to evidence or suggestions it sought and obtained help from Russia.

Several official US investigations are continuing.

Facebook disclosed earlier this month that an influence operation that appeared to be based in Russia had purchased $100,000 in ads to promote divisive political and social messages in a two-year period.

The adverts had spread controversial views on topics such as immigration, LGBT rights and race and had promoted 470 “inauthentic” pages and accounts that Facebook later suspended, according to the company. Facebook has said it was cooperating with related federal investigations, and the revelations have lended credence to the findings of US intelligence officials that Russia was involved in influencing the 2016 presidential election.

Concerns about the role of political ads on Facebook have not been limited to the US. A series of Conservative party attack ads in the UK were sent to voters in a key marginal constituency and relied on dummy Facebook accounts, the Guardian reported earlier this year.

On Thursday, Facebook’s general counsel Colin Stretch said in a statement: “After an extensive legal and policy review, today we are announcing that we will also share these ads with congressional investigators. We believe it is vitally important that government authorities have the information they need to deliver to the public a full assessment of what happened in the 2016 election.”

The announcement comes one day after 20 Democratic senators and representatives wrote to the Federal Election Commission to urge it “develop new guidance” for advertising platforms “to prevent illicit foreign spending in US elections”.

In his speech, Zuckerberg said Facebook would also create a “new standard” for transparency in political advertising so advertisers must disclose which page paid for an ad and so that the public can visit advertisers’ pages and see the ads they’re currently running to any audience on the site.

Zuckerberg said the company had also been working to ensure the integrity of the forthcoming German election and had taken action against thousands of fake accounts.