A Swedish diplomat leaked classified and sensitive political information about the EU to Russia, a Swedish newspaper reported Wednesday, quoting a defected Russian foreign intelligence officer.

"He gave us large amounts of information and documents, especially about how former Soviet states were trying to approach the EU and NATO," Sergei Tretyakov told the Expressen daily.

Tretyakov said the diplomat, who was not named, was recruited in the late 1990s in New York, where he had regular meetings with Russia's foreign intelligence service, the SVR in 1999 and 2000.

Codenamed Silverster by the Rusians, he supplied classified information from the European Union's internal information system, Coreu.

"He was valuable. He gave us constant and relevant access to up-to-date information," Tretyakov told Expressen.

"The documents we received from Silvester related among other things to the conflict in the former Yugoslavia around Kosovo, and that was of course of the greatest interest to Russia," he said.

"He was a very important source ... He (also) told us about information that he received during discussions with other diplomats," he added.

The diplomat himself, who is reportedly still working in Sweden's foreign ministry, acknowledged to Expressen that he had been in contact with Russian "representatives" during his New York posting, but insisted Tretyakov's description of events was "misleading".

The paper also reported that Sweden's security police Saepo had been informed about the Swede's activities by the CIA, and that prosecutor Tomas Lindstrand had launched an investigation into the espionage charges in 2002.

After just three months, however, the probe was discontinued, since the information the diplomat had access to was primarily political.

"For it to be considered espionage, I need to prove that the leaked information harmed national security, and that is difficult to prove in this case which involves political information," Lindstrand told Expressen.