India recorded more than 45,000 cases of the deadly "black fungus" over the last two months, the health ministry said, as a nationwide outbreak sweeps through Covid-19 patients.

The country's junior health minister Bharati Pravin Pawar told parliament on Tuesday that over 4,200 people had died of the fungus -- scientific name mucormycosis.

The infection was previously considered very rare but cases have ballooned during the pandemic, usually striking patients after recovery from Covid-19.

It is a highly aggressive disease and surgeons have been forced to remove eyes, the nose and jaw from patients to stop it spreading to the brain.

The death rate is over 50 percent.

According to government data, the highest number of cases were reported in the western state of Maharashtra at 9,348.

India dealt with just 20 cases a year on average before the pandemic, with only people with severely compromised immunity at risk, including those with high blood sugar levels, HIV or organ transplant recipients.

Experts have attributed the recent rise to the excessive use of steroids to treat Covid-19.

The Indian government declared the fungus an epidemic in May as cases shot up and social media has been flooded with desperate pleas for medicines to treat the illness.

Government data tabled on Tuesday suggested infection numbers peaked during May and June and have since substantially decreased.

But the Hindustan Times newspaper reported Monday that there had been a rise in cases among children in the northern state of Rajasthan.