NEW DELHI, March 30 (Xinhua) -- Indian police have grilled senior officials of the Central Board of Secondary Examination (CBSE) in connection with the leak of question papers that led to the cancellation of the tenth standard mathematics and the twelfth standard economics board exams.

"CBSE's Controller of Examinations was interrogated for over four hours by the Delhi police sleuths Thursday evening. CBSE's exam in-charge and two other officials were also grilled," a police official said Friday.

Earlier Thursday, police detained the owner of a tutorial center in Delhi and questioned over 25 students and private teachers in connection with the leak of question papers.

"Vicky, the owner of Vidya Coaching Centre in Delhi, has been taken into police custody for questioning. He is one of the main suspects in the question paper leak. His tutorial center is suspected to be the origin of the leaks," a police official said.

Meanwhile, CBSE chief Anita Karwal said that the board exams would be conducted again. "The decision to hold fresh exams in the two papers for some 2 million students has been taken in favour of children."

Indian Prime Minister Narendra Modi has already expressed his unhappiness over the leak of the exam papers and asked the Human Resource Development (HRD) Ministry to take strict actions.

"I just want to tell the parents and children that it is extremely unfortunate that this incident happened. Those behind the leaks will not be spared and that a special investigation team has been formed to investigate the issue," HRD Minister Prakash Javadekar said Wednesday.

"We have taken serious note of the issue. It looks like some sort of gang is behind this. The prime minister has asked us to take strict actions against all involved," he added.