British military officers will be sent to Libya to advise rebels fighting Colonel's forces, the UK government has said.
Foreign Secretarysaid the group would be deployed to the opposition stronghold of Benghazi.
The BBC understands that 10 UK officers will provide logistics and intelligence training, part of a joint British and French operation.
Mr Hague stressed that the officers would not be involved in any fighting.
When the UN Security Council passed its resolution on Libya in March, foreign military action on the ground was specifically ruled out.
He said: "The [UK] National Security Council has decided that we will now move quickly to expand the team already in Benghazi to include an additional military liaison advisory team.
"This contingent will be drawn from experienced British military officers."
The announcement comes as hundreds of people are feared dead in the bombardment by Pro-Gaddafi forces of the town of Misrata.