BRUSSELS, Jan 20 (Reuters) - European Union foreign ministers agreed on Monday to send up to 1,000 soldiers to help stabilize Central African Republic, the EU's first major military operation in six years, a diplomatic source said.

Ministers meeting in Brussels approved an outline plan to send a battalion-sized force to the violence-torn country but detailed military plans still need to be worked out.

EU officials hope to get United Nations Security Council authorization for the mission this week and also that the force will start arriving in Central African Republic by the end of February. It will be based around the capital Bangui.

It is not yet clear which EU countries will contribute troops. Estonia has promised soldiers, and Lithuania, Slovenia, Finland, Belgium, Poland and Sweden are among countries considering sending troops, diplomats say.

Large EU countries such as Britain, Germany and Italy have said they will not contribute.

Central African Republic descended into chaos after a mostly Muslim rebel coalition, Seleka, seized power in March, unleashing a wave of killings and looting that sparked revenge attacks by Christian militia.