President Barack Obama has warned that his administration is preparing measures to counter Chinese cyber commercial espionage, in a shot across the bow as President Xi Jinping prepares to visit the US.

Speaking to the Business Roundtable in Washington, Mr Obama said cyber espionage would “probably be one of the biggest topics that I discuss with President Xi”. The US president said he accepted that China and other nations, including the US, would pursue traditional espionage, such as trying to obtain transcripts of his conversations, but stressed that stealing commercial secrets was “an act of aggression that has to stop”.

“We are preparing a number of measures that will indicate to the Chinese that this is not just a matter of us being mildly upset, but is something that will put significant strains on the bilateral relationship if not resolved and that we are prepared to take some countervailing actions in order to get their attention,” Mr Obama told business leaders.