The Swedish Authority for Privacy Protection (IMY) was hit by an overload attack early on Tuesday morning, and was still offline at the time of publication at around 2:30pm, hours later.

According to Swedish newspaper Aftonbladet, a pro-Russian group claimed on communications app Telegram that it had attacked the authority’s website, as well as other Swedish websites.

IMY was unable to confirm the information when asked by the TT news agency.

“We don’t know who’s behind this,” IMY spokesperson Per Lövgren said.

The website of the Swedish Financial Supervisory Authority was also down on Tuesday, according to Aftonbladet. It however appeared to be back up and running in the afternoon.

An overload attack sends more traffic to its target than it can handle, making it impossible for regular users to visit the website.

The attack is the latest in a spate of cyber attacks targeting Swedish businesses and public authorities in recent weeks, although the extent to which they’re linked or not is unknown.

This week, hacker group Medusa listed information it stole from Stockholm’s Sophiahemmet hospital for sale on the dark web, asking for a million US dollars to delete the data.

Last week, Bjuv, a small municipality of some 16,000 residents in southern Sweden, received threats from Russian hacker group Akira that it would leak data it stole from the municipality.

Last month a major attack on IT supplier Tietoevry by Akira affected tens of thousands of employees at Swedish businesses and agencies, forcing some shops to close for several days.