Libya's EU ambassador Hadeiba Hadi has defected along with his staff, the latest in a string of top diplomats to end their support for Muammar Gaddafi's government.
"After more than four months of the blood-letting of our people, my colleagues and myself at the Libyan popular bureau in Brussels find ourselves obliged to announce our decision to no longer represent the regime," he said in a statement.
European Union foreign policy chief Catherine Ashton welcomed his decision to sever links with the Tripoli regime in protest over the violence.
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"We have been in contact with him and praise his courageous decision to work for a democratic Libya and a better future for the Libyan people," her office quoted her as saying.
The ambassador's statement also said he and his staff were placing themselves "at the service of the Libyan people in its struggle for democracy, the rule of law and institutions, and the safeguard of the integrity of our country."
Ashton said: "Those at the top of the Gaddafi regime have a choice: Stay with Gaddafi and face rejection by their fellow citizens and the international community.
"Or support efforts to ensure that the hopes and expectations of the Libyan people are realised through democracy."
A European diplomatic source described Hadi as "a Libyan diplomatic heavyweight".
"His defection leaves the Gaddafi regime increasingly isolated."
Several leading Libyan diplomats have quit the Libyan leader's side in recent weeks, including the ambassadors for the United States, France, Portugal and even Paris-based UNESCO.
Former foreign minister Moussa Koussa, also one-time Libyan intelligence chief between 1994 and 2009 and a member of Gaddafi's innermost circle, defected to London on March 30.
US Secretary of State Hillary Clinton has said oil minister Choukri Ghanem has also left and is in Tunisia but Tripoli has denied the claim.
