A joint director of the Enforcement Directorate, who probed the 2G scam and Aircel Maxis case, has made a scathing attack on Revenue Secretary Hasmukh Adhia questioning him if he has developed animosity against him by "siding with scamsters and their affiliates".

In his letter dated June 11, 2018 forwarded to the Revenue Secretary by ED Director Karnal Singh, Joint Director Rajeshwar Singh asked a series of uncomfortable questions from Mr Adhia ranging from ignoring his promotion, "compromising National security", "set scores on an ego trip" among others.

Meanwhile, sources in the finance ministry said charges levelled by Rajeshwar Singh against the Revenue Secretary are absolutely baseless.

The letter became public through informal channels after Supreme Court today told the government that it was free to look into the "serious" allegations against Mr Singh apparently withdrawing the immunity from probe given by it to the officer earlier.

The Supreme Court's observations came after the counsel of central government submitted a secret report in sealed cover apparently carrying details of a phone call received by Mr Singh from Dubai.

The Central government also told the court that it was open for investigations of allegations against Mr Singh.

While Mr Adhia did not reply to messages sent to him seeking comments, sources in the finance ministry said charges levelled by Mr Singh against the Revenue Secretary are absolutely baseless.

"The officer of ED who is under a cloud, as acknowledged by Supreme Court also, is now trying to make undue allegations just to save his skin. If he is a clean officer why is there a need for him to worry? Let independent inquiry prove so," a source said.

The source said as the court has taken cognisance of the facts, let an independent inquiry/ investigation be done.

"If he is clear and transparent then he should not worry about these things," the source said.

"The wild allegations of harassment and denial of his due promotion are baseless. From time to time appropriate action with regard to promotion has been taken as per rule. The government will go within the scope of the law and as per court's order," he said.

However, the Enforcement Directorate, an agency under the Finance Ministry, issued a formal statement in support of its Joint Director saying he is a responsible officer with outstanding career records.

In its statement, the Directorate said, "To put the record straight Dr Rajeshwar Singh received a call in 2016 from a person based out of Dubai who gave important information regarding a case being investigated by the Enforcement Directorate."

"Dr Rajeshwar Singh passed on this information to the Directorate and the same was used in the investigation of the case. It is important to note that he received only one call and that too it was an incoming call from this person in Dubai," the agency said.

Mr Singh, a UP police officer had joined the directorate on deputation, today went on leave as the "atmosphere against him was hostile", sources close to him said.

The Supreme Court maintained that the Centre was free to look into the "serious" charges against ED officer Rajeshwar Singh, probing the "highly sensitive" 2G spectrum allocation scam cases including the Aircel-Maxis deal.

"You are simply an officer. You can't be given a blanket clean chit. Everybody is accountable. You must be accountable for any action. We need to ensure that you are accountable. We don't want to damage you or comment against you. There are very serious allegations against you," the Bench of Justices Arun Mishra and S K Kaul told the officer.

In the letter to Mr Adhia, Rajeshwar Singh has said, "It pained me further that you have expressed many a times to senior officers over casual conversations that I have been manipulating the judiciary, especially the Supreme Court of India."

"It is strange and also unbelievable that after so many years in public service, you believe that so many judges can be manipulated and that too over such a long period of time," he said.

The officer said journalist Rai, who was intimidating him and leading malicious campaign against him, his investigations and his office, has access to corridors of power in the Finance Ministry.

"Your silence on this issue is misunderstood by many to be your implicit support for the fixers of his ilk to demonise officers who believe in their convictions," he said.

He said former finance minister P Chidambaram "sported an open and direct grudge against him" because of Supreme Court monitored Aircel-Maxis investigation.

"However, what thoroughly baffles the undersigned, is the animosity you have fashioned against me by siding with scamsters and their affiliates in a sustained manner. It has become more than difficult for me to survive this continued onslaught and persistent vilification from all the quarters for doing my job," he said.

Mr Singh alleged his promotion became due from April 1, 2017 but it has not yet been processed in the ministry as officers close to Adhia are raking up complaints, levelled by journalist Upendra Rai, against him in the Central Vigilance Commission.

"I am astutely aware that this is being done to not just humiliate me but also to ensure that the investigation in certain crucial cases I handle, ought to derail. May I beg to ask if you are compromising on larger aspects of our national interest to set scores on an ego trip that is absolutely uncontested from my side," he said.