Russia yesterday revealed holding a Chinese national for the past year on espionage charges linked to repair manuals for a missile system that Beijing had been buying from Moscow for years.

The rare public spy spat between the two giants emerged just days before a visit to China by Prime Minister Vladimir Putin – a former intelligence agent who plans to return to the Kremlin for up to 12 more years in power in March.

China issued no comment while Russian officials stayed mum about why they kept the unusual case quiet since making the initial arrest on October 28 last year.

The FSB domestic security service said the case of Tong Shengyong was forwarded by prosecutors to the Moscow City Court on Tuesday.

“The investigation established that the Chinese national (was) working on assignment from the Ministry of Public Security of the People’s Republic of China,” FSB said in a statement.

It said Tong had posed as an interpreter for “official delegations” and tried to purchase data from Russian nationals. The espionage charge carries a prison sentence of 10 to 20 years.

The S-300 system is an older version of Russian surface-to-air missiles that Moscow has produced since the Soviet era and has since replaced with the more modern S-400.