Joint Director of Central Bureau of Investigation (CBI) official, Rishi Raj Singh, who has been investigating the Adarsh Housing society scam, has been transferred to Economic Offences Wing in Mumbai.

The transfer came at the time when CBI was expected to file a supplementary charge-sheet in the housing scam.  

Singh's transfer is likely to kick off a fresh debate over Congress-led UPA government's approach in tackling corruption cases, as this development comes just 24 hours after the CBI sleuths filed the first charge-sheet in the housing scam on Wednesday. 

The timing of the CBI official's transfer could be questioned by the opposition parties as an attempt to sabotage the investigating process by the Centre, which involves high profile people like former Maharashtra CM Ashok Chavan, army officers and other top officials. The CBI's charge-sheet, which runs upto about 10, 000 pages, accused 13 people of scam, including Chavan. The Congress leader has been accused of granting some favours to the housing society members in a quid-pro-quo manner. 

However, the CBI department has claimed the transfer of Singh has a routine process.  

Keshav Kumar will now lead the probe into the Adarsh scam case following the transfer of Singh.

Meanwhile, Singh will replace officer Kandaswamy, who retired a few months back. The top post at Economic Offence Wing in Mumbai, was vacant since Kandaswamy's departure.

Adarsh scam came to light in November 2010, following the fall out of the housing scam then Chief Minister of Maharashtra Chavan was forced to resign the post.

Maharashtra BJP Writes to PM

The Maharashtra BJP unit on Friday wrote a letter referring to Prime Minister Manmohan Singh and Home Minister P Chidambaram and sought not to transfer the CBI investigator, Singh.

Vinod Tawde, a BJP leader in Maharashtra, has noted that transferring the officer in the housing society scam, when the investigation is still on is ""inappropriate and should be stopped."