Authorities in Bahrain say they have arrested a person who arrived from Iraq and who was trying to smuggle bomb-making materials into the restive Gulf island nation.

The police said in a statement on Monday that the suspect was arrested while arriving on a bus at a border post on the causeway linking the island with Saudi Arabia. Bomb-making materials found on the bus were seized. The suspect was not identified.

Bahrain has faced four years of unrest following widespread anti-government protests led by the country's Shiite majority against its Sunni monarchy.

Young protesters routinely clash with riot police. A number of small bombs mainly targeting security forces have killed and wounded police officers in the unrest.