Though the US military has in place protection that could give its navigation systems a high-degree of robustness, most civilian GPS systems have none, Mr Parkinson said. He also warned that the EU's new €5bn Galileo satellite system, created as an alternative to the US-controlled GPS, was equally at risk.
Richard Peckham, who helped develop the Galileo system, said that although its public service was encrypted, making it more difficult to hack and more secure for users such as the emergency services and public utilities, it was still vulnerable to jamming and interference.
The US, which initially opposed the European satellite constellation, has come around to supporting it, in part because Washington has realised it needs a GPS back-up system that is neither Russian nor Chinese.
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A report compiled for the UK government and released this week warned that "the conditions are present for a catastrophic 'Black Swan' event" that would knock out one or more critical GPS systems. The report identified thousands of instances of GPS jamming occurring annually.
Disruption of satellite navigation systems has so far remained a relatively low-level problem for governments. Small-range jamming devices can be acquired easily via the internet. However, more powerful jamming equipment is becoming increasingly easy to acquire.
Over the past few years South Korea has witnessed huge jamming attacks against its GPS systems, launched by North Korea. The areas affected stretch 100km into South Korean territory, and include major airports and shipping lanes. More than 1,000 ships and 250 planes had their travel disrupted by North Korean jamming attacks in 2012.
(Read more: US unveils measures to avoid 'cyber Pearl Harbor')
Seoul has responded by ordering the construction of a land-based antenna array over more than 40 sites to provide a back-up system.
The UK has already begun to build a similar system, primarily to help shipping in the event of GPS disruption. The stretch of water between Britain and France is one of the busiest shipping lanes in the world, but navigation throughout it could be disrupted by a single portable jamming device.
"When a ship loses GPS, it isn't like a car satnav," said Professor David Last, a consultant to the UK's General Lighthouse Authority. "Multiple systems fail simultaneously."
Prof Last cited a report into navigation vulnerabilities from the Royal Academy of Engineering that found "there was barely a single area of commerce or industry in the UK that wasn't dependent on GPS in some way."