U.N. Secretary-General Ban Ki-moon has appointed former British diplomat Derek Plumbly as his special coordinator for Lebanon, effectively the top U.N. official in the Middle Eastern country, Ban's office announced on Friday.

Plumbly succeeds Michael Williams, also British, who held the job from 2008-11. The announcement came on the day Ban himself visited Lebanon.

Plumbly, 63, is an Arabic speaker who worked for the British Foreign Office for some 30 years, including serving as ambassador to Saudi Arabia and later Egypt. Most recently he headed a commission monitoring Sudan's north-south peace deal.

The United Nations has a 12,000-strong peacekeeping force in Lebanon known as UNIFIL.

(Reporting By Patrick Worsnip)