The Chinese government has been accused by the US Senate of orchestrating cyber-attacks on military targets and commercial defence contractors over a year-long period.

Military airlines and computers onboard a commercial ship were attacked around 50 times between 2012 and 2013, according to a new report published by the Senate.

"These peacetime intrusions into the networks of key defense contractors are more evidence of China's aggressive actions in cyberspace," said Carl Levin, chairman of the Senate Armed Services Committee.

"Our findings are a warning that we must do much more to protect strategically significant systems from attack and to share information about intrusions when they do occur."

Civilian air, shipping, and other tranportation assets used by the military in times of crisis were targeted by hackers attributed to the Chinese government.

Around 20 of the 50 intrusions were apparently successful and presented an "advanced persistent threat" to a network of contractors.

"We must ensure that cyber intrusions cannot disrupt our mission readiness" said Senator Jim Inhofe, the committee's ranking member.

"It is essential that we put into place a central clearinghouse that makes it easy for critical contractors, particular those that are small businesses, to report suspicious cyber activity without adding a burden to their mission support operations."

The allegations - the latest in the long-running cyberwar between the US and China - have been denied by the Chinese government, with embassy officials in Washington calling the claims "groundless".

In response to the investigation's findings, the committee included a provision in its version of the National Defense Authorization Act for next year directed at addressing reporting gaps in its cyber-defence infrastructure.

It is hoped that such provisions will improve the way in which the Department disseminates information about cyber intrusions into the computer networks of operationally critical contractors.