Australia‘s federal parliament says it has launched an investigation after its computer network was compromised by an unspecified “security incident”.

In a statement on Friday, parliamentary authorities said they had taken “a number of measures” to protect the network and its users.

There was no official comment on the nature of the cybersecurity breach, but the statement said there was no initial proof that data had been accessed.

“We have no evidence that this is an attempt to influence the outcome of parliamentary processes or to disrupt or influence electoral or political processes,” it said.

“Our immediate focus has been on securing the network and protecting data and users.”

The breach forced parliamentarians and staff members to reset their computer passwords as a precaution.

Sophisticated actors involved?

Prime Minister Scott Morrison said he had been briefed on the matter, adding: “There is no suggestion that government departments or agencies have been the target of any such incursion.”

The Australian Signals Directorate (ASD) confirmed it was working with parliament in response to the breach, a move that indicates that sophisticated actors may be involved.

National broadcaster ABC reported intelligence agencies were looking into whether a foreign government could be behind the attack.

“To undertake such an attack, you need some big resources, so a state actor is most likely,” James Der Derian, director of the Centre for International Security Studies at the University of Sydney. told Reuters news agency.

“You have to look and see who has a grievance against Australia, and the most obvious suspects would be China and Russia.”

In December, officials in the United States and Britain said businesses and government agencies in the two countries and at least 10 others – which did not include Australia – were the victims of a massive data theft carried out by state-sponsored Chinese hackers.

Beijing has denied the accusations, saying they are “deliberate defamation” pulled “out of thin air.”

Media reports this week said Australia rescinded the visa of a prominent Chinese businessman just a few months after barring Chinese telecoms giant Huawei Technologies from supplying equipment to its 5G broadband network.

Australia’s ties with Russia, meanwhile, soured after the downing of Malaysian Airlines flight MH17 in 2014, brought down by a Russian surface-to-air missile. Moscow has denied involvement.