HELSINKI (AP) — A Russian citizen has been detained in Estonia over suspicions of spying and preparing a computer crime on behalf of Russia's domestic security agency, prosecutors said Tuesday.

The detention of the man, who was not identified, means "bigger damage was prevented," prosecutor Inna Ombler said. She said Estonian state institutions were targeted but didn't disclose details.

The man was caught over the weekend in Narva, an Estonian border town, on his way to Russia, Ombler said. Russia's consulate general in Estonia's third largest city, some 200 kilometers (124 miles) east of Tallinn, said it had not been informed of the detention of a Russian citizen.

Ombler said the man was working for the Russian Federal Security Service, or FSB — the main KGB successor agency — against Estonia and had committed "a serious crime."

Estonian newspaper Postimees — quoting unnamed sources at the prosecutors' office — said the case was not related to an ongoing upgrade of the security features in Estonians' ID cards.

Some 760,000 Estonians need to upgrade the microchip card's security certificate to continue to safely use a wide array of digital government and private services provided in the Baltic country.

Ombler said no other individuals are under investigation.

In recent years, Estonia has caught several spies working for Moscow, chiefly Estonian citizens but also Russians. In 2016, three men — whose nationalities were not revealed — were convicted and jailed for cooperation with Russian special services in Estonia. Russian diplomats in the country also have been expelled.

Estonia's security and foreign intelligence services have repeatedly said Russia's intelligence services have a strong interest in the Baltic NATO member and former Soviet republic.

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Jan M. Olsen in Copenhagen contributed to this story.