Tapuria was arrested here after three days of questioning, ED sources said.
Meanwhile, Khan's chartered accountant, Sunil Shinde, has been asked to appear before the ED for questioning. The ED had conducted searches at his residence in Pune yesterday.
53-year-old Khan has been arrested by the agency on charges of stashing huge amounts of black money in banks abroad. He is also facing a Rs 70,000-crore tax demand notice from the Income-Tax department.
The I-T department has raised a tax demand of Rs 591 crore against Tapuria and Rs 20,540 crore against his wife Chandrika.