Ranchi: The Central Bureau of Investigation (CBI) on Saturday arrested three people, including a key "mastermind" and two MBBS students, allegedly involved as "solvers" in the NEET paper leak case, media reported.

Officials identified the mastermind as Shashikant Paswan, also known as Sashi or Pasu, a B.Tech graduate from the National Institute of Technology (NIT) in Jamshedpur, news agency PTI reported.

He allegedly connived with Kumar and Rockey, who had been arrested earlier, according to the report.

One of the solvers, Kumar Mangalam, is a second-year MBBS student from Bharatpur, Rajasthan. The other accused, Dipendra Sharma, is also a second-year MBBS student from Bharatpur.

Both were in Hazaribagh on May 5, the day of the NEET-UG exam, allegedly acting as solvers for the paper stolen by Pankaj Kumar, an engineer who was previously arrested.

With these new arrests, the total number of individuals detained by the CBI in six cases related to alleged NEET-UG irregularities has reached 21.

On Friday, the CBI also arrested Surabhi Kumari, a first-year MBBS student at Ranchi's Rajendra Institute of Medical Sciences (RIMS), for allegedly being part of the solver module. She was taken into custody after two days of questioning.

Pankaj Kumar, also known as Aditya, a 2017-batch civil engineer from the National Institute of Technology Jamshedpur (Jharkhand), is accused of stealing the NEET-UG paper from the NTA trunk in Hazaribagh.

Earlier in the week, the CBI approached RIMS, an autonomous institute under the Jharkhand government, for questioning, which led to Kumari's arrest.

On Thursday, the CBI had arrested four MBBS students from AIIMS Patna, all part of the solver module.

According to sources, these solvers were responsible for solving the exam paper to provide answer keys to NEET aspirants who had sought the services of the paper leak gang.

The central probe agency has registered six FIRs related to the alleged irregularities in the medical entrance exam.