The five nations in the world's leading intelligence-sharing network have been exchanging classified information on China's foreign activities with other like-minded countries since the start of the year, seven officials in four capitals said.

The increased cooperation by the Five Eyes alliance — grouping Australia, Britain, Canada, New Zealand and the United States — with countries such as Germany and Japan is a sign of a broadening international front against Chinese influence operations and investments.

Some of the officials, who spoke on condition of anonymity because of the sensitivity of the talks, said the enhanced cooperation amounted to an informal expansion of the Five Eyes group on the specific issue of foreign interference.