Image copyright ALEXANDRIA SHERIFF'S OFFICE Image caption Kevin Mallory, 62, was convicted under the Espionage Act

A former CIA officer has been jailed for 20 years for disclosing military secrets to a Chinese agent, the US justice department says.

Kevin Mallory, 62, was found guilty of several spying offences following a two-week trial last June.

The fluent Mandarin speaker from Leesburg, Virginia, held top-level security clearance and had access to sensitive documents.

He was convicted of selling secrets to China for $25,000 (£19,600).

Evidence at his trial included a surveillance video which showed him scanning classified documents onto a digital memory card at a post office.

He also travelled to Shanghai to meet with a Chinese agent in March and April 2017, the justice department said.

"Mallory not only put our country at great risk, but he endangered the lives of [people] who put their own safety at risk for our national defence," US attorney Zachary Terwilliger said in a statement.

"This case should send a message to anyone considering violating the public's trust and compromising our national security," he added. "We will remain steadfast and dogged in pursuit of these challenging but critical national security cases."

The Justice Department said Mallory held a number of sensitive jobs with government agencies.

He had worked as a covert case officer for the CIA and as an intelligence officer for the Defense intelligence Agency (DIA).

"This case is one in an alarming trend of former US intelligence officers being targeted by China and betraying their country and colleagues," Assistant Attorney General John Demers said following the sentencing.

Earlier this month, ex-CIA agent Jerry Chun Shing Lee pleaded guilty to spying for China. Prosecutors said the naturalised US citizen was paid to divulge information on US covert assets.

And last June, former US intelligence officer Ron Rockwell Hansen was also charged with attempting to spy for China.

He attempted to pass on information and received at least $800,000 (£600,000) for acting as a Chinese agent, the justice department said at the time.

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Image copyright AFP Image caption Chinese police guard the US embassy in the capital, Beijing