The £2.4bn Bowman digital communications programme was supposed to replace the army's outdated analogue combat radio system, Clansman, by 1995. The full deployment of Bowman is delayed until 2007.
Clansman, which is based on 30-year-old technology, is renowned for its poor levels of security. The MoD admitted on its website that the system is "insecure except at formation level and is becoming increasingly obsolete".
During the war in Kosovo there were reports of British soldiers using mobile phones in an attempt to avoid communications being monitored by the enemy.
The MoD has been forced to invest in another system as a stopgap. The Personal Role Radio from Marconi Mobile was issued to 45,000 users last year. However, the radio is a basic, short-range system that lacks security.
An MoD spokesman said, "The limitations of Clansman are well known and we are working within those limitations." He also confirmed that the Personal Role Radio was not secure.
He said the MoD had put enhancements in place designed to make armed forces communications more secure for the current campaign, but declined to go into details.
When it is delivered, Bowman will provide all three armed services with a more secure, IP-based platform for voice and data communications which, it is hoped, will be more interoperable with allies' systems.
Bowman will include land-based command and control systems and provide the infrastructure to support future digitisation applications. It also uses Global Positioning System technology to help prevent friendly-fire incidents.
The MoD has a poor record of delivering complex technology projects. A report from the National Audit Office last December slammed the department for underestimating the risks involved in major projects and for time slippage in procurement programmes.