The Central Bureau of Investigation (CBI) has arrested the chief investigator in the coal blocks allotment case for allegedly accepting a bribe of Rs7 lakh to "settle" a land dispute for a businessman.

A second CBI officer and two others were arrested as well.

The arrests were carried out by the CBI's internal intelligence unit.

The arrested persons are Superintendent of Police Vivek Dutt and Inspector Rajesh. They were arrested outside the CBI's headquarters here on Friday.

The alleged bribe money was found on Dutt. The two officers will be produced before a special CBI judge on Saturday.

The alleged bribe is not connected with the coal case which is being monitored by the Supreme Court, sources said.

However, the agency cannot change its investigating officer without the court's permission.

CBI Director Ranjit Sinha said the agency would inform the Supreme Court about Friday's arrests, adding that the CBI had been maintaining surveillance on the three for some time.

Dutt heads the CBI's cyber cell, and is alleged to have given a report favourable to the alleged bribe giver on a case that was referred to the CBI by the Delhi Police.