LONDON (Reuters) - Britain has sent 40 military personnel to Tunisia to provide training aimed at helping the North African country prevent the spread of Islamic State fighters from neighboring Libya, the British defense minister said on Saturday.

The training will focus on operational planning, intelligence, surveillance and mobile patrolling and is the third mission of its kind by British troops in Tunisia since 30 British holidaymakers were killed in a beach attack there.

The massacre in June last year at a hotel in Sousse on the Mediterranean coast was the biggest loss of British lives in such an incident since the July 2005 bombings in London.

"We are determined to support our Tunisian allies to defend against Daesh (Islamic State) terrorists who slaughtered innocent Britons on a beach there last year," Defence Secretary Michael Fallon said in a statement.

"Our training will help Tunisian forces strengthen their border security and stop the spread of Daesh along the coast."

The training will be delivered to around 200 Tunisian army personnel at various locations. Two previous training missions took place in February and late last year.

(Reporting by Estelle Shirbon; Editing by Kevin Liffey)