The alleged ringleader of a terror group accused of attacking Americans and Kuwaiti security forces has died of heart failure while in prison, an Interior Ministry official said Wednesday.

Amer Khlaif al-Enezi (search), believed to be in his 30s, died Tuesday, said the official, speaking on condition of anonymity.

He was arrested Jan. 31 in a police raid on a house in Mubarak Al Kabir, south of Kuwait City (search). He was questioned by state security and then referred to the prosecution.

The government has been locked in a battle against militant Muslims since last month. Al-Enezi and scores of other terror suspects were being questioned by the prosecution on accusations of plans to attack the country's state security as well as American civilians and members of the U.S. military.

Kuwait is a major ally of Washington but its militants widely oppose the U.S. military presence in their country. Since 2002, they have attacked the U.S. military and American civilians working for them, killing a Marine and a contractor