The Uttar Pradesh Anti-Terrorism Squad arrested a suspected Islamic State group operative from Mumbai airport on Saturday night. He was returning from Saudi Arabia when he was arrested, the Uttar Pradesh Police said on Sunday.

The man, Abu Zaid, has now been brought on transit remand to Lucknow, the police said.

There was a lookout notice against Zaid ever since another group of four suspected Islamic State operatives was arrested in April. Zaid was the “ideologue of his group”, and was arrested based on the propaganda messages he exchanged with those arrested earlier, said the police.

He had been in Saudi Arabia for the last year-and-a-half. The police said an investigation about his activities is under way.