PRAGUE (AP) — The Czech Republic's foreign minister said Tuesday that his email account and the accounts of dozens of ministry officials have been successfully hacked.

The January cyberattack was sophisticated, and experts believe it was done by a foreign state, Foreign Minister Lubomir Zaoralek said.

Zaoralek did not specify the country suspected of being behind the hack, but said it was similar to the theft of Democratic National Committee emails in the United States.

U.S. intelligence agencies have alleged that email accounts of prominent Democrats were hacked as part of a campaign ordered by President Vladimir Putin to influence the presidential election in favor of Donald Trump. Moscow denies the allegation.

In the Czech Republic, experts from the National Cyber Security Centre, spy agencies and the foreign ministry have been investigating the January attack and taking measures to prevent more in the future.

Prime Minister Bohuslav Sobotka called the attack "serious."

"The issue has to be thoroughly investigated," he said.

The breach was discovered during a security check. Zaoralek said a large amount of data was involved, but he told a news conference that no classified information had been compromised.

He said the case shows a need for funding to ensure the country's cybersecurity.

Zaoralek said experts have to check out whether any other state institutions have been targeted for similar attacks.

He said his ministry has faced cyberattacks before, but none were successful until now.