LONDON: Russia’s Federal Security Service (FSB) said on Thursday it had uncovered a US National Security Agency (NSA) plot using previously unknown malware to access specially made so-called backdoor vulnerabilities in Apple phones.

The FSB, the main successor to the Soviet-era KGB, said that several thousand Apple phones had been infected, including those of domestic Russian subscribers.

The Russian spy agency also said telephones belo­nging to foreign diplomats based in Russia and the former Soviet Union, including those from Nato members, Israel, Syria and China, had been targeted.

Neither Apple nor the NSA immediately respo­nded to emailed requests for comment outside usual US business hours.

The FSB said the plot showed the close relationship between Apple and the NSA, the US agency responsible for US cryptographic and communications intelligence and security.

“The hidden data collection was carried out through software vulnerabilities in US-made mobile phones,” Russia’s foreign ministry said in a statement.

“The US intelligence services have been using IT corporations for decades in order to collect large-scale data of Internet users without their knowledge,” the ministry said.

Shortly after Russia sent its troops into Ukraine last year, US and British spies claimed a scoop by uncovering intelligence that President Vladimir Putin was planning to invade. It is still unclear how that intelligence was gained.