Norway on Monday summoned a Chinese diplomat to protest against an "unacceptable" cyberattack on the IT systems of its parliament in March.
The Norwegian parliament said at the time it had been targeted in a global cyberattack on Microsoft Exchange Servers blamed on Chinese state-backed groups.
The parliament had been hit by another hack seven months earlier blamed on a Russia-based group.
"We summoned the embassy of China earlier in the day," Foreign Minister Ine Eriksen Soreide told a news conference.
"We clearly told them that this sort of attack is unacceptable."
She added that the attack was carried out "from China" but stopped short of directly blaming the Chinese state.
The United States, the European Union, and Britain have blamed China for the March cyberattack.
In 2010, China reacted angrily after the Nobel peace prize was given to jailed Chinese dissident Liu Xiaobo.
The incident affected ties between Oslo and Beijing even though the award is made by an independent panel.