The Enforcement Directorate (ED) headquarters in south Delhi was sealed for 48 hours on Saturday and Sunday after several employees tested positive for the novel coronavirus.
Among those who tested positive are Special Director (HIU) and Investigating Officer handling the aviation scam involving corporate lobbyist Deepak Talwar.
Staff in the legal and intelligence section have also tested COVID-19 positive. Ten staff members have been quarantined.
The office was shut after deep sanitisation work was undertaken.
On Thursday, a floor of the office was sealed for two days after a staff member tested positive for COVID-19, news agency IANS reported.
The ED operates from two floors at the Loknayak Bhawan and at that time only one floor of the ED office had been sealed.
Meanwhile, on Monday, four staff members of the Department of Revenue of the Finance Ministry tested positive for coronavirus. In an office memorandum, the department said that the entire North Block has been deeply sanitised.