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BEIRUT, June 30 (Reuters) - Lebanon's army said on Thursday it had foiled planned terrorist attacks by Islamic State on a tourist site and a crowded area, days after suicide bombers killed five people in a Christian village.

Five people involved in the two thwarted attacks, including the mastermind, were arrested, an army statement quoted by the National News Agency said.

"Those arrested confessed to having carried out terrorist acts against the army previously. Investigations are continuing," the statement said.

Lebanon's government warned this week of a heightened terrorist threat after eight suicide bombers targeted a Christian village on the border with Syria on Monday, killing five people.

Sunni Muslim militants have repeatedly struck in Lebanon since the eruption of the war in Syria. A bombing attack in a mostly Shi'ite area of southern Beirut, which was claimed by Islamic State, killed more than 40 people in November.

Lebanese authorities have arrested some 120 Syrians from makeshift refugee camps in the country since Monday's attacks, a security source said.

(Reporting by John Davison; Editing by Andrew Heavens) ((John.Davison@thomsonreuters.com;))