AMSTERDAM (Reuters) - All ballots in the Netherlands’ election next month will be counted by hand in order to preserve confidence in the electoral system after reports suggested its automated counting systems may be vulnerable to hacking, the government said.

Intelligence agencies have warned that three crucial European elections this year, in the Netherlands, France and Germany, could be vulnerable to manipulation by outside actors, including Russia.

“Reports in recent days about vulnerabilities in our systems raise the question of whether the results could be manipulated,” Interior Minister Ronald Plasterk said in a statement on Wednesday. “No shadow of doubt can be permitted.”

He told broadcaster RTL that possible external actors included Russia. “Now there are indications that Russians could be interested, for the following elections we must fall back on good old pen and paper,” he said.

The Dutch cast paper votes, which are tallied by hand locally. However, the regional and national collation of vote tallies are done electronically.

Dutch media have reported that the software used may not be secure.

In an earlier report, RTL had said the tallying software was distributed by CD-ROM to regional counting centers where it was installed on old computers that were internet connected - a procedure that experts consulted by the broadcaster considered highly insecure.

Plasterk told RTL the vote count should not take longer than normal. Election authorities typically publish a preliminary result on the evening after polls close, which is often very close to the final outcome.

The March 15 parliamentary vote, in which the anti-immigration and anti-European Union Freedom Party is expected to make gains, sets the scene for later French and German polls at a time when Brexit, opposition from the new Trump administration and a newly assertive Russia have placed the EU under unprecedented strain.

Russia has been linked with backing, both formal and informal, for destabilizing far right movements in Europe and the United States, while U.S. intelligence has alleged that Russia has hacked U.S. political parties’ e-mails. Russia has denied interfering in the U.S. election.