Russia's state arms export corporation Rosoboronexport insisted on Monday, Dec 3, it had not received any formal notification from the U.S. regarding cancellation of a contract for delivery of Russian military helicopters to Afghanistan, RIA Novosti reported.

That follows a vote in the Senate last Thursday to ban Rosoboronexport from any further U.S. government contracts, in response to Russia continuing to supply weapons to the Assad regime in Syria. The ban could come into force as soon as January 1, 2013.

"All will be clear when the US President makes a decision. There is no decision yet - it's a recommendation. The contract remains in force as yet," a Rosoboronexport source said.

The Pentagon announced in June plans to buy ten more Mi-17 helicopters for the Afghan military from Rosoboronexport, in addition to an earlier $367.5 million contract signed in May 2011 for delivery of 21 Mi-17V5s.

The total value of the deal including engineering services and spare parts could be around $900 million, U.S. officials said then.

The U.S. Defense Department acts as an intermediary in purchasing some military equipment for Afghanistan's military where it is paid for by U.S. government aid, in order to prevent corruption.

Afghanistan prefers Russian-made helicopters to Western-designed machines as they are cheaper, and the country has a tradition of using them dating back to the 1980's. Recently, Afghan crew members have been trained to fly and maintain Mi-17s in the UK by British military instructors, the UK Defense Ministry said.

The U.S. imposed sanctions on Rosoboronexport in 2008 in response to it claimed were breaches of arms control regime agreements regarding Iran. Rosoboronexport and the Russian government have repeatedly denied any infringement of arms export controls regarding Iran or Syria.

President Barack Obama lifted the sanctions against Rosoboronexport in May 2010.