The Enforcement Directorate (ED) on Monday played down concerns after a major fire ripped through one of its Mumbai offices, fuelling speculation over the fate of key case files the central probe agency is working on.

The fire erupted around 2.25am on Sunday at the agency's Mumbai Zonal Office-I housed in the Kaiser-I-Hind building at Ballard Estate.

The blaze continued for almost 10 hours, raising concerns that investigation records for several high-profile cases including those of fugitive businessmen Mehul Choksi and Nirav Modi, as well as politicians Chhagan Bhujbal and Anil Deshmukh, might have been destroyed.

Officials confirmed that furniture and certain documents were burnt, though they insisted that investigations would not suffer as critical files had digital backups and were stored in a centralised system.

The agency attributed the blaze to a short-circuit in the power boxes on the fourth floor.

It said the offices on the ground and first floors remained unaffected and operational, while the scorched fourth floor's operations had been shifted to an old regional office at Janmabhoomi Chambers.

"There is no impediment in conducting investigations or trials," the ED said in a statement, adding that original evidentiary documents in prosecution cases were lodged with the respective courts.

NCP (Sharad Pawar) leader Supriya Sule called the incident "serious" and questioned why it took nearly 12 hours to douse the flames in an area that is neither congested nor difficult to access.

Speaking to reporters, Sule asked, "In an area without parking congestion or crowds, how could it take so long for the fire engines to control the blaze? Fire safety norms and the building’s audit must be scrutinised."

On concerns over the loss of sensitive files linked to high-profile investigations, Sule added, "If the ED doesn't have backup copies of the files, it would be shocking."

The ED said the fire was first detected by staff and security personnel, who informed state police on night duty. Firefighting operations began around 3.30 am, involving more than 50 personnel and multiple tenders.

The agency also noted that efforts were underway to secure a standalone office at the Bandra-Kurla Complex, where the Maharashtra government had allotted land to the ED earlier this year.

Even as the agency reassured that investigations into Choksi, Modi, and others such as Chhagan Bhujbal and Anil Deshmukh would continue unhindered, Opposition leaders are unlikely to let the smoke clear without a closer look.

(With inputs from PTI)