Mumbai,  In a massive embarrassment, the Central Bureau of Investigation (CBI) said that it has raided and arrested its own sleuth for allegedly conniving to prepare a 'purported' clean-chit to former Maharashtra Home Minister Anil Deshmukh, here on Thursday.

The raids took place in New Delhi and Allahabad while the arrest took place early Thursday, hours after the CBI had swooped on Deshmukh's son-in-law Gaurav Chaturvedi and his Nagpur-based lawyer Anand Daga late on Wednesday evening, from Worli in Mumbai.

The Chaturvedi-Daga duo was detained and their statements recorded till the wee hours when the complicity of an inside hand, the CBI's own official -- a Sub-Inspector Abhishek Tripathi -- was also confirmed.

The CBI said in a terse statement this morning that it has registered a case against its own SI, the Nagpur-based lawyer (Daga) and other unknown persons for certain allegations, including corruption.

"During the investigations of the said case, CBI has today arrested the SI (Tiwari), while the lawyer (Daga) is being questioned," the agency said, even as raids were carried out in New Delhi and Allahabad and his personal lockers in the CBI offices here.

It maybe recalled that last weekend, media and political circles were rocked by a report purportedly giving a 'clean-chit' given to Deshmukh in the Bombay High Court-ordered preliminary enquiry (PE).

Rattled by the alleged leak, the CBI had issued two strong rebuttals on the issue, and quietly launched a probe into the matter which culminated in the nabbing of an 'inside hand' in the sordid episode.

The unsigned-undated-unattributed alleged PE report triggered a fresh political row with the Nationalist Congress Party and Congress demanding that the CBI should comment on the authenticity or otherwise of the report.

As a fallout of the incident, the CBI picked up Chaturvedi and Daga on Wednesday and early Thursday, nabbed its own (CBI) sleuth for allegedly conniving with them to prepare the fake PE report.

Slamming the move, State Congress Spokesperson Sachin Sawant said it was extremely "extremely serious" as they were taken away without serving any notice.

"The laws are being trampled and the country is run by 'Modi-Shah'... 'Whatever we say is the law', the Modi government should officially declare," said Sawant.

NCP National Spokesperson and Minister Nawab Malik said that they were taken away "illegally, without any prior intimation or notice", raising questions if there is rule of the law in the country or the law of the rulers.

"The CBI must clarify under what laws and norms the action was taken without following the due process of law," Malik said sharply.

There has been speculation in some circles that Deshmukh, who's on the radar of the ED and CBI but has yet to respond to their multiple summons, may be in contact with his family members.