LONDON (AP) -- European Union regulators said Tuesday they're investigating whether TikTok breached the bloc's digital rulebook by failing to deal with risks to Romania's presidential election, which has been thrown into turmoil over allegations of electoral violations and Russian meddling.

The European Commission is escalating its scrutiny of the popular video-sharing platform after Romania's top court canceled results of the first round of voting that resulted in an unknown far-right candidate becoming the front-runner.

The court made its unprecedented decision after authorities in the European Union and NATO member country declassified documents alleging Moscow organized a sprawling social media campaign to promote a long shot candidate, Calin Georgescu.

"Following serious indications that foreign actors interfered in the Romanian presidential elections by using TikTok, we are now thoroughly investigating whether TikTok has violated the Digital Services Act by failing to tackle such risks," European Commission president Ursula on der Leyen said in a press release. "It should be crystal clear that in the EU, all online platforms, including TikTok, must be held accountable."

The European Commission is the 27-nation EU's executive arm and enforces the bloc's Digital Services Act, a sweeping set of regulations intended to clean up social media platforms and protect users from illegal content. It ordered TikTok earlier this month to retain all information related to the election.

In the preliminary round of voting on Nov. 24 Georgescu was an outsider among the 13 candidates but ended up topping the polls. He was due to face a pro-EU reformist rival in a runoff before the court canceled the results.

The declassified files alleged that there was an "aggressive promotion campaign" to boost Georgescu's popularity, including payments worth a total of $381,000 to TikTok influencers to promote him on the platform.

TikTok said it has "protected the integrity" of its platform over 150 elections around the world and is continuing to address these "industry-wide challenges."

"TikTok has provided the European Commission with extensive information regarding these efforts, and we have transparently and publicly detailed our robust actions," it said in a statement.

The commission said its investigation will focus on TikTok's content recommendation systems, especially on risks related to "coordinated inauthentic manipulation or automated exploitation." It's also looking at TikTok's policies on political advertisements and "paid-for political content."

TikTok said it doesn't accept paid political ads and "proactively" removes content for violating policies on misinformation.

The investigation could result in TikTok making changes to fix any problems, or in fines worth up to 6% of the company's total global revenue.