JOHANNESBURG (miningweekly.com) – London-listed Petra Diamonds on Monday said it had temporarily idled the operations of its 75%-owned Williamson mine, in Tanzania, for “health and safety and security reasons”, as key personnel cooperate with authorities over a blocked diamond shipment.

The company on Monday confirmed that a parcel of 71 654.45 ct of diamonds recovered from the mine had been confiscated on route to Petra's marketing office in Antwerp, Belgium, with certain, undisclosed key personnel from Williamson currently being questioned by the authorities.

In an update to shareholders, Petra assured that the grounds “upon which these actions have been taken” had not been formally made known to the company as yet.

However, media reports have been quoting Tanzania's Finance and Planning Ministry as saying that Petra had allegedly “cheated” in the declaration of the value of the diamonds, with a “fresh evaluation” by government revealing a nearly $15-million discrepancy.

“Government has complete oversight of the diamonds produced at the mine, which are physically controlled by a number of different government representatives in conjunction with Petra from the point of recovery until the point of sale,” Petra assured in the statement.

Defending its stance, Petra said it was the responsibility of government's diamonds and gemstones valuation agency to provisionally valuate the diamond parcels from Williamson before they are exported to Antwerp and said that all of the necessary documentation for the shipment, including the diamond valuation certificate issued by the Ministry of Energy and Minerals, is freely available for viewing.

These documents also included the receipts confirming the company’s payment of the provisional royalty and associated fee relating to the diamond parcel, the Kimberley Process Certificate and the company’s invoice for shipping purposes.

“The Williamson mine is held 75% by Petra and 25% by the government of the United Republic of Tanzania, and Petra confirms that all operations related to the mine are conducted in a transparent manner and in full compliance with legislation in Tanzania and the Kimberley Process,” Petra stated.