(Bloomberg) -- Authorities in the Netherlands detained two Russian nationals earlier this year who were suspected of planning a break-in at a Swiss lab that is investigating the poison attack on Sergei Skripal in the English town of Salisbury, according to Dutch and Swiss reports.

The Russians were detained in the Hague, NRC Handelsblad said Friday, citing the results of joint reporting with Swiss newspaper Tages-Anzeiger. The suspects were planning to travel to the Spiez Laboratory, a government-run facility in central Switzerland that investigates nuclear, biological and chemical weapons, and had in their possession equipment to break in, according to the newspapers.

Spokespeople for the Hague’s Prosecutor’s office, the Dutch military intelligence MIVD unit and Dutch prosecutor’s office responsible for international investigations declined to comment on the reports.

“We had several indications that there were some hacking attempts during the last few months,” including attempts to plant malware that would spread to other labs, Andreas Bucher, a spokesman for the Spiez Laboratory, said by telephone. “But we were not compromised.”

Tages-Anzeiger reported last week that the two Russians who carried out the Salisbury attack made repeated trips through Geneva. Both suspects are said to have been working for Russia’s GRU intelligence service, but were not the same people accused by British authorities for the Salisbury poisoning of Skripal, a former Russian agent, and his daughter Yulia, according to the papers.

A spokesperson for the Russian Defense Ministry, of which the GRU is a unit, wasn’t immediately available to comment.

The two suspects for the planned lab attack were returned to Russia without prosecution in the Netherlands or extradition to Switzerland, according to Tages-Anzeiger.

Swiss NDB intelligence services have been working with their Dutch and British counterparts on the case, according to the papers. The Swiss Attorney General’s office has been investigating the two suspects for espionage since March 2017 and identified the pair arrested in the Hague, the papers said.

The Swiss AG’s office said in a statement that it opened criminal proceedings at that time into two individuals on suspicion of political espionage “in a different context.” Beyond confirming the Swiss Federal Intelligence Service’s collaboration, the AG’s office didn’t elaborate further. Swiss Intelligence didn’t immediately return a request for comment.

The NRC reported that the Organization for the Prohibition of Chemical Weapons had asked the Swiss facility to confirm a U.K. lab’s findings that the Skripals had been targeted with a “military grade” nerve agent developed by Russia, known as “Novichok,” which it did.

The OPCW declined to comment, citing confidentiality.

--With assistance from Catherine Bosley and Stepan Kravchenko.

To contact the reporters on this story: Wout Vergauwen in Amsterdam at wvergauwen@bloomberg.net;Hugo Miller in Geneva at hugomiller@bloomberg.net

To contact the editors responsible for this story: Lukas Strobl at lstrobl@bloomberg.net, ;Anthony Aarons at aaarons@bloomberg.net, Christopher Elser, Thomas Mulier

©2018 Bloomberg L.P.

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