Leaked documents reportedly show that Chinese spies hacked large amounts of data relating to the design of the F-35 Joint Strike Fighter jet.
Media reports suggest the alleged cyber theft is revealed in documents leaked to the German magazine Der Spiegel by former US security analyst Edward Snowden.
The F-35 is a stealth bomber developed by the US-based defence firm Lockheed Martin. The Royal Air Force is among the major customers for the jet.
The Sydney Morning Herald cites one document as saying that the theft amounts to "many terabytes of data" including information about the F-35's radar systems, engines and method for cooling exhaust gases.
The UK is set to send more warships to Bahrain's Mina Salman Port as it establishes a new £15 billion military base in the Gulf state.Read the full story ›
The Ministry of Defence has made a "huge investment" after awarding £3.2 billion of contracts to support the management of the UK's naval bases and help sustain more than 7,500 jobs.
BAE Systems, which manages HMNB Portsmouth, has been awarded a £600 million contract while Babcock, which manages Devonport and Faslane, has been given a £2.6 billion deal.
The Royal Navy's warships and submarines will be maintained and repaired as part of the deal, the MoD said.
This huge investment in our naval bases will directly sustain more than 7,500 jobs and skills across the UK and ensure that the Royal Navy's fleet of 56 warships and submarines are in the best possible condition and available for operations.
The contract will secure around 1,500 jobs at Faslane on the Clyde, up to 4,000 posts at HMNB Devonport and more than 2,000 at Portsmouth.
The Prime Minister has pledged 3,500 British troops to take part in exercises in eastern Europe in 2015 and 2016.
The Prime Minister has pledged 1,000 British troops to a "high readiness" Nato force, Downing Street has said.
When the force is ready, in late 2015, it will be capable of deploying within 2-6 days.
British troops will make up a substantial portion of the multinational force, which will total 4,000 troops.
The Ministry of Defence announced today a deal to buy new £48 million state-of-the-art missile system for Royal Navy helicopters.
The defence minister Philip Dunne said the system made in east Belfast by the defence company Thales UK "will help win battles."
Mr Dunne said coastlines represented areas of growing concern to armed forces around the world and this new technology would provide greater protection.
The system will be used to target small ships and fast attack craft and be designed and built by Thales UK's Belfast plant.
Conservative MP Rory Stewart has been elected the new chair of the House of Commons Defence Select Committee, taking over from fellow Tory James Arbuthnot.
Mr Stewart, who represents the Cumbria constituency of Penrith and The Border, has served in the army and the diplomatic service, along with running a charity in Afghanistan.
The Government has dodged criticism that it is not clear enough on its military intervention policy, saying it will allow the House of Commons to debate before sending troops to overseas crisis.
A Government spokesman said:
The decision to use UK armed forces overseas is among the most significant a Government can make.
That's why the Government has stated that it will observe the existing convention that says the House of Commons should have the opportunity to debate before UK troops are committed to conflict, except in cases where the urgency of the action required makes this impossible.
Military intervention as a course of action can of course be contentious and contested but the Government is clear that it remains an important last resort when all other means of dealing with threats have been exhausted.
Opting out of military intervention in international crisis has "implications for the UK's place in the world," MPs have warned.
A report from the Defence Select Committee said:
We understand and acknowledge the current lack of appetite for military operations given the experiences and tensions of the past decade for operations in countries such as Afghanistan and Iraq.
However, it is also necessary to understand and acknowledge that there are consequences to decisions by the UK and the international community not to intervene in humanitarian or non-humanitarian situations.
Non-intervention decisions have implications for the UK's place in the world and its influence which are as profound as a decision to undertake an intervention operation.
The Government should set out a "realistic vision" of the circumstances which would force the UK to join military intervention abroad, a committee of MPs have recommended.
The cross-party Defence Select Committee called on the Coalition to set clear parameters for the kind of behaviour which would force them to send troops abroad.
MPs also called on David Cameron's Government to clearly define the UK's place in the world.
Committee members warned the implications of not joining some crisis were just as profound as sending troops abroad.
The MPs suggested Russia may have felt empowered to intervene in Ukraine because the UK and other countries had failed to act in Georgia or Syria.