Abu Hamza, a key figure allegedly involved in the planning of the deadly Mumbai attacks of 2008, has been arrested in Delhi, Indian police say.
Abu Hamza, also known as Syed Zabiuddin, has been remanded to police custody, said an Indian senior police official.
He is being described as the “handler” of the 10 gunmen who carried out the deadly assault on targets in Mumbai.
The attacks claimed 165 lives. Nine gunmen were also killed.
The sole surviving gunman from the attacks, Mohammad Ajmal Amir Qasab, was convicted of murder and waging war on India in May 2010 and given a death sentence.
The 60-hour siege of Mumbai began on 26 November 2008, targeting luxury hotels, the main railway station and a Jewish cultural centre.
Relations between India and Pakistan hit rock bottom after India blamed the Pakistan-based militant group Lashkar-e-Taiba for the attacks.
After initial denials, Pakistan acknowledged that the assault had been partially planned on its territory and that Qasab was a Pakistani citizen.