The Federal Prosecutor’s Office arrested three men in Frankfurt on Wednesday who are suspected of espionage for a foreign secret service. The Karlsruhe authority announced this on Friday.

The men were brought before the investigating judge at the Federal Court of Justice on Thursday, who issued and executed the arrest warrants.

“The three accused were travelling in Germany on behalf of a foreign secret service to gather information on a person from Ukraine who was staying here,” the top German prosecutor’s office said. On Wednesday, they scouted out a cafĂ© in Frankfurt where the Ukrainian target was supposed to be.

According to the Federal Prosecutor’s Office, the suspected agents are a Ukrainian, an Armenian and a Russian citizen. They are “strongly suspected” of having worked for a foreign secret service. The arrest was carried out by officers of the Hessian State Office of Criminal Investigation.