The advisors will go into the country's second city of Benghazi — the stronghold of the pro-democracy opposition.
Foreign Secretary William Hague said today: "The 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."
Mr Hague said the move was needed to help protect civilians in Libya and was compatible with the United Nations resolution which authorised a no-fly zone.
He said in a statement: "The United Kingdom is strongly committed to the effective implementation of the provisions of United Nations Security Council Resolution (UNSCR) 1973.