TUNIS (Reuters) - Tunisia said on Thursday it had broken up four Islamist militant cells and seized explosives, poisonous gas and drone aircraft.

The militants had been planning a “series of attacks against vital targets in the country, through stabbing, poisoning, cars attacks and detonation,” the interior ministry said, without identifying any targets.

The seizures came a month after a woman blew herself up in the center of the Tunisian capital and wounded 15 people in an attack that broke a period of calm after dozens died in militant attacks three years ago.

Tunisia was the only country to oust a long-serving autocrat during the “Arab Spring” uprisings without triggering large scale unrest or civil war - and has won widespread praise for its democratic transition, new constitution and free elections.

But authorities estimate about 3,000 Tunisians have joined Islamic State and other jihadist groups in Iraq, Syria and neighboring Libya, while high unemployment has stoked unrest in recent years in southern and central areas.