Image copyright AFP Image caption Kun Shan Chun worked for the FBI for 19 years

An FBI employee with top secret security clearance has pleaded guilty to acting as an "agent of the Chinese government", the US says.

Kun Shan Chun, a naturalised US citizen born in China and known as Joey, admitted in court to sending sensitive information to a Chinese official.

US Attorney Preet Bharara said he had threatened the country's security through a "duplicitous" betrayal.

Chun "deeply regrets" what he did and loves the US, his lawyer said.

While he could face a sentence of up 10 years in prison, the government and defence agreed a sentence of between 21 and 27 months "would be appropriate", the New York Times reports, citing the plea agreement.

The Chinese Embassy in Washington is yet to comment, the Associated Press reports.

'Financial rewards'

Chun, 46, worked for the FBI as an electronics technician from 1997 until his arrest in March.

He was introduced to a Chinese government official during a trip to Italy and France in 2011, the Department of Justice says, and they continued to meet privately abroad.

He is accused of having covered up his connections with at least one Chinese government official and a Chinese technology company, Zhuhai Kolion, in which he had an "indirect financial interest", according to the justice department.

Court papers in New York said in 2013 he sent an unnamed Chinese official a chart showing the FBI's organisational structure and two years later sent photos of restricted documents about surveillance technologies.

Chun also provided the identity and travel schedule of an FBI agent, Assistant US Attorney Emil Bove said.

He was rewarded financially and through perks such as holidays and hotel stays, according to authorities.

According to the complaint, he was caught after offering to help an undercover agent transmit sensitive government information to his Chinese associates.