TUNIS, July 19 (Xinhua) -- Tunisia arrested an extremist who was planning an attack against a security unit, the Interior Ministry said Sunday.

"Thanks to the close coordination between Tunisia's intelligence services and various security units, an extremist, who pledged allegiance to the extremist group Islamic State, was arrested," said a ministry statement.

An in-depth investigation confirmed that this extremist had been trained to manufacture explosives and tried to obtain necessary materials to carry out an attack against a security unit, according to the statement.

Tunisia has started to witness terrorist acts since 2011, with dozens of security and military agents, civilians and foreign tourists having been killed.