Thousands of UK political ads went missing from Facebook archive searches.

Axar.az reports citing Reuters that Facebook’s ad library, which it launched in the UK in 2018, is a public tool for users to view political advertising on the platform.

The problem, first reported by Sky News, affected ads from the ruling Conservative Party, the Brexit Party and the Liberal Democrats. It was not immediately clear if any Labour Party ads were affected.

“We have fixed the bug and all of the impacted ads in the UK are now back in the ads library,” Facebook said in a statement.

A spokesman also confirmed that some ads in the United States were affected, but declined to answer questions on the scale of the issue there.

Facebook has also come under fire in recent months over its decision not to fact-check political ads. Chief Executive Mark Zuckerberg has defended that stance by arguing Facebook does not want to stifle free speech, but he has also said the company will look at how the policy could be refined.