Russia is continuing to delay its plan to declassify precious metals data, with details of platinum group metals reserves remaining undisclosed.

The Natural Resources Ministry told Reuters that the long-awaited process has been postponed once more.

"That's what has been decided,” explained ministry spokesman Rinat Gizatulin. “This is not so much the decision of the Natural Resources Ministry but of the various coordination committees representing relevant ministries."

Mr Gizatulin was vague about the reasons behind the delay, commenting: "I not am saying this is the way it is going to be forever."

The plans to declassify the data came into law back in February after a vote in the Duma, but they need backing from President Vladimir Putin before they are officially enacted.

The disclosure of pgm data is designed to make the Russian market more appealing to foreign investment and remove some of the layers of secrecy that have surrounded the sector for many years.

One of the sticking points for the move is thought to be the fact that the law does not cover stocks held by the state - with officials seeking to protect its interests.