India announced Tuesday a partial lifting of a fresh export ban on a malaria drug seen as a potential coronavirus treatment, after US President Donald Trump hinted at "retaliation".

Citing domestic needs, India banned on Saturday exports of hydroxychloroquine which has shown early promise against COVID-19 in small-scale studies in France and China.

India is the world's largest producer and exporter of the drug, according to media reports. Global stocks are however limited and Trump said that he had pressed Indian Prime Minister Narendra Modi this weekend to expedite shipments, hinting at consequences otherwise.

"If he doesn't allow it to come out, he doesn't allow it to come out, that would be okay, but of course, there may be retaliation, why wouldn't there be?" Trump said on Monday.

The Indian foreign ministry swiftly backtracked and on Tuesday said it would now license the export of the drug and paracetamol -- exports of which were restricted in March -- "in appropriate quantities to all our neighbouring countries who are dependent on our capabilities."

"We will also be supplying these essential drugs to some nations who have been particularly badly affected by the pandemic," foreign ministry spokesman Anurag Srivastava said in a statement.

He added that they would be "kept in a licensed category and... continuously monitored."

Trump has strongly touted hydroxychloroquine as a coronavirus treatment although many scientists are urging caution until larger trials show whether it is safe and effective.

Hydroxychloroquine and another drug, chloroquine, have been used for decades against malaria but they have potentially serious side effects, especially in high doses or administered with other medications.

The European Medicine Agency warned last week that the two drugs should not be used to treat COVID-19 cases, except for clinical trials or in the event of a "national emergency".

The Times of India reported that New Delhi had also come under pressure from Australian Prime Minister Scott Morrison and from other countries including Britain, France, Germany and Brazil over pharma exports.