- Kable, Friday 3 July 2009 10.33 BST
They are aimed at improving the performance of the Bowman system, providing more equipment for users, upgrading planning and system management applications, and improving interoperability with other allied systems.
Under the first contract, known as Capability Release 1.5 and valued at £119m, General Dynamics will update the system's capabilities over its lifetime to reflect advances in technology. The second, valued at £112m, will provide longer term technical support for the Bowman programme and will include repairs, field services and the provision of spares.
Quentin Davies, the minister for defence equipment and support, said: "Bowman has been used successfully in Iraq and Afghanistan, where secure, faster communications and data exchange is saving lives on the front line. It is a key element of a comprehensive suite of communications systems to provide a robust network that allows commanders to exercise command and control effectively.
"These contracts are testament to our work with industry which allows us to rapidly adapt to technological advances and the evolving operational demands of our front line troops."
The MoD added that the work will help to sustain several hundred jobs at the General Dynamics' Oakdale site in South Wales.
Bowman's secure radio communications and basic data capability have been used on operations since 2005.
