Below is the full text of a British government note explaining what it regards as the legal basis for using British military forces in Libya:
"Following the Prime Minister's statement to the House on 18 March, this note sets out the Government's view on the legal basis for the deployment of UK forces and military assets to Libya.
Under the Charter of the United Nations the Security Council is the organ conferred with primary responsibility for the maintenance of international peace and security. In carrying out its duties the Security Council acts on behalf of Member States of the United Nations, who agree to accept and carry out its decisions in accordance with the Charter. Among the specific powers granted to the Security Council are those provided in Chapter VII of the Charter which is concerned with action with respect to threats to the peace, breaches of the peace and acts of aggression.
Security Council resolution 1973 (2011) of 17 March 2011 is annexed to this document.
In this resolution the Security Council has determined that the situation in the Libyan Arab Jamahiriya constitutes a threat to international peace and security. The Security Council has adopted the resolution as a measure to maintain or restore international peace and security under Chapter VII of the United Nations Charter, which provides for such action by air, sea and land forces as may be necessary to maintain or restore international peace and security.
Provision for a No Fly Zone is provided for by operative paragraphs 6 to 12 of the resolution. Operative paragraph 8 authorises Member States that have notified the UN Secretary-General and the Secretary-General of the League of Arab States, acting nationally or through regional organisations or arrangements to take all necessary measures to enforce the ban on flights established by operative paragraph 6.
Operative paragraph 4 of the resolution also authorises Member States making the notifications so provided, and acting in co-operation with the UN Secretary-General, to take all necessary measures to protect civilians and civilian populated areas under threat of attack in the Libyan Arab Jamahiriya, including Benghazi, while excluding a foreign occupation force of any form on any part of Libyan territory.
Operative paragraph 13 of the resolution, in substituting a replacement operative paragraph 11 in resolution 1970 (2011), further authorises Member States to use all measures commensurate to the specific circumstances to carry out inspections aimed at the enforcement of the arms embargo established by that earlier resolution.
The Attorney General has been consulted and Her Majesty's Government is satisfied that this Chapter VII authorisation to use all necessary measures provides a clear and unequivocal legal basis for deployment of UK forces and military assets to achieve the resolution's objectives."