The United States must beef up cybersecurity against Chinese hackers targeting a broad range of U.S. interests to raise the cost to China of engaging in such activities, America's top intelligence official said on Thursday.

The testimony by Director of National Intelligence James Clapper before a congressional committee added to pressure on Beijing over its conduct in cyberspace just weeks before Chinese President Xi Jinping makes a state visit to Washington.

Presenting a dire assessment of global cyberthreats, Clapper said China and Russia posed the most advanced cyberthreats but that Iran and North Korea could also cause serious disruptions despite having less sophisticated technology.