The US Congress will now evaluate the four-year deal which would involve the US providing professional military training as well as administrative and management advice.

The National Guard will also receive light armoured vehicle training, as well as guidance on maintenance and repair work and related logistics issues. If all options are exercised, the deal will be worth $1.8bn.

The contract would run from 1 January 2009 to 31 December 2013, and form part of a strategy in Riyadh to retrain the National Guard to handle upgraded weapons systems.