British Army officers are being sent to Libya to advise rebels fighting Muammar Gaddafi's forces.
The UK group will be deployed to the opposition stronghold of Benghazi, Libya's second city, in a mentoring role to help leaders co-ordinating attacks on the dictator's army.
The announcement came after a Royal Navy submarine launched cruise missiles on Libyan targets, with RAF warplanes attacking communication masts.
The handful of experienced officers will join a British team in Benghazi working with the opposition National Transitional Council (NTC), which Foreign Secretary William Hague described as "legitimate political interlocutors".
Mr Hague said the Army officers would help prevent attacks on civilians, in line with the United Nations (UN) Security Council resolution authorising military action against Gaddafi's forces.
He said: "These additional personnel will enable the UK to build on the work already being undertaken to support and advise the NTC on how to better protect civilians.
"In particular they will advise the NTC on how to improve their military organisational structures, communications and logistics, including how best to distribute humanitarian aid and deliver medical assistance."
The Foreign Secretary added: "Our officers will not be involved in training or arming the opposition's fighting forces.
"Nor will they be involved in the planning or execution of the NTC's military operations or in the provision of any other form of operational military advice."
Britain has supplied rebels with body armour and telecommunications equipment and the Government yesterday pledged £2 million to help thousands of stranded civilians flee war-torn Misrata by boat.
Speaking to Sky News, Mr Hague again ruled out a ground invasion to unseat Gaddafi, but admitted further SAS raids were possible for specific missions.
Prime Minister David Cameron last week faced demands to recall Parliament from Easter recess so MPs could debate the ongoing crisis after Mr Cameron signalled his support for regime change in the North African nation.
Conservative John Baron said then: "The mission in Libya has changed quite significantly. When it was put before the House, the emphasis was very much on humanitarian assistance. This has changed into a mission of regime change."
Mr Hague said today: "We had the overwhelming support of Parliament. The policy remains exactly the same as it was then - to implement UN Security Resolution 1973."
But he admitted: "Of course developments change on the ground and what we have to do in order to implement the Resolution does change."
Labour MP David Winnick criticised the British officers' deployment, saying: "There is a danger of mission creep. This is a big escalation of Britain's involvement."
Senior Liberal Democrat MP Sir Menzies Campbell warned: "Sending advisers for a limited purpose is probably within the terms of resolution 1973, but it must not be seen as a first instalment of further military deployment.
"Vietnam began with an American president sending military advisers. We must proceed with caution."
Meanwhile, Major General John Lorimer, strategic communications officer to the Chief of Defence Staff, outlined the latest attacks by British jets on Col Gaddafi's military sites.
He said: "A Tornado and Typhoon attacked a pair of multiple rocket launcher vehicles and a light artillery piece which had been observed firing on Misrata, then guided in a second pair of RAF aircraft to destroy a self-propelled gun and tank which were being brought into the area on a tank transporter."
Images released by the Ministry of Defence and filmed from by a British jet showed a communication mast being lined up in plane's crosshairs before a bomb destroys the site.
The Royal Navy nuclear-powered submarine HMS Triumph fired Tomahawk cruise missiles early yesterday, which were timed to coincide with RAF bombing raids.
Maj Gen Lorimer added: "It will take time for the full impact of these attacks to become clear."
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