Prime Minister David Cameron has said the UN resolution on Libya is about saving lives and imposing a no-fly-zone is "the right thing to do".
The “exceptional circumstances” in Libya justified action against Colonel Qadhafi, Mr Cameron said.
Speaking in the House of Commons following the UN resolution, the PM said all criteria for intervention had been met.
…we’ve always been clear that preparing for eventualities which might include the use of force - including a no fly zone or other measures to stop humanitarian catastrophe - would require three tests to be met.
Demonstrable need. Regional Support. And a clear legal basis.
The Resolution demands an immediate establishment of a ceasefire and a complete end to violence and attacks on civilians.
It also establishes “a ban on all flights” in the airspace of the Libya in order to help protect civilians and authorises Member States to take “all necessary measures to enforce compliance with the ban”.
Earlier today, the Cabinet held an emergency meeting and agreed the UK will play its part.
Our forces will join an international operation to enforce the resolution if Qadhafi fails to comply with its demand that he ends attacks on civilians.
Preparations to deploy these aircraft have already started and in the coming hours they will move to bases from where they can start to take the necessary action.
In an interview following news the Qadhafi regime had declared a ceasefire, the PM said the UN Security Council resolution was about “protecting lives, protecting civilians and stopping slaughter” and Britain would judge Qadhafi “by his actions not his words”.
The Prime Minister will travel to France tomorrow for talks on Libya with President Sarkozy and UN Secretary General Ban Ki-moon.
Read more: Statement in the House of Commons