COPENHAGEN (Reuters) -Unexplained electronic components have been found in imported equipment for Denmark's energy supply network, industry group Green Power Denmark said on Wednesday, adding that an investigation was underway to learn more.

The findings coincide with an increased focus internationally on potential security vulnerabilities in critical infrastructure such as energy grids.

"It concerns printed circuit boards that were supposed to be part of components for the energy supply," Jorgen Christensen, technical director at Green Power Denmark, told Reuters.

"We don't know how critical it is or whether there are bad intentions behind it," he said.

The Danish ministry for preparedness and resilience declined to comment on whether an investigation had been started. The justice ministry, energy ministry and the intelligence service did not reply to Reuters' requests for comment.

Christensen declined to specify which country the equipment originated from, who was conducting the investigation or to elaborate on the components' capabilities, including whether they were meant for solar power equipment.

"This is highly concerning. It is important that an investigation is underway," Walburga Hemetsberger, CEO of solar lobby SolarPower Europe, told Reuters on Wednesday.

Christensen said the components were discovered recently during a routine examination of circuit boards that were due to be installed in energy supply equipment.

The circuit boards might have been designed for multiple purposes, which could explain the presence of additional components, but Christensen emphasised they should not be included in equipment destined for energy infrastructure.

"It's possible the supplier had no malicious intent. We can't say at this point, but that doesn't change the fact that these components shouldn't be there," he said.

The findings were first reported by Danish news outlet Berlingske earlier on Wednesday.

Reuters last week reported that U.S. energy officials found rogue communication devices in Chinese-made solar inverters and batteries that could potentially bypass firewalls and destabilise power grids.

(Reporting by Stine Jacobsen in Copenhagen and Sarah McFarlane in London. Editing by Jane Merriman)