India has partially eased restrictions on the export of anti-malarial drug hydroxycloroquine, refusing to cave in to a threat of “retaliation” from US President Donald Trump if New Delhi turned down his request to lift the hold on American orders.

Hydroxychloroquine tablet is seen as a viable therapeutic solution to cure Covid-19 disease that has so far affected over a million people across the world.

People familiar with developments, who spoke on condition of anonymity, said orders from other countries for hydroxycloroquine and paracetamol will be cleared only after meeting all domestic requirements.

India, the largest producer of hydroxycloroquine, initially banned exports of the drug on March 25 to ensure adequate domestic supplies. The rules were tightened on April 4 by barring exports of hydroxycloroquine and formulations made from it from special economic zones (SEZs) and export-oriented units (EOUs). Such bans don’t usually apply to SEZs and EOUs, which are meant to promote exports.

However, both Trump and Brazil President Jair Bolsonaro had called on India government to permit the supply of the drug to cope with Covid-19 cases in their countries.

“There has been a partial lifting of the ban, and hydroxycloroquine and paracetamol exports will continue to be restricted,” said one of the people cited above who declined to be named.

“Depending on availability of stocks of hydroxycloroquine after meeting domestic requirements, existing orders will be cleared,” the person said.

The department of pharmaceuticals under the ministry of chemicals and fertilizers and the external affairs ministry will decide on allocations on a case-to-case basis, depending on the humanitarian situation related to the Covid-19 pandemic, the people said.

Trump, who has repeatedly advocated the use of hydroxycloroquine to fight Covid-19 despite opposition from some of his top advisers, told a White House briefing on the Coronavirus outbreak on Monday that there could be “retaliation” if India turns down his request to lift the hold on US orders.

The US president had requested the lifting of the hold on hydroxychloroquine exports during a telephone call with Prime Minister Narendra Modi on Sunday. The US had placed orders for the medicine in March.

“I said we’d appreciate you allowing our supply to come out. If he doesn’t allow it to come out, that would be okay but, of course, there may be retaliation,” Trump said. “Why wouldn’t that be?”

“I don’t like that decision,” Trump said, referring to India’s move to bar exports of hydroxychloroquine. “I didn’t hear that that was his [Modi’s] decision. I know that he stopped it for other countries. I spoke to him yesterday [Sunday]. We had a very good talk, and we’ll see whether or not that’s his decision. I would be surprised if he would you know because India does very well with the US.”

Trump also reiterated his long-standing grievances on trade issues with India, saying: “For many years they’ve been taking advantage of the US on trade. So I would be surprised if that was the decision. He’d have to tell me that.”

Brazilian President Bolsonaro, facing tremendous pressure at home for his handling of the Covid-19 crisis, too said he had sought supplies of hydroxychloroquine from India. “I asked the PM of India for his support in continuing the supply of pharmaceutical inputs for the production of hydroxychloroquine. We will spare no effort to save lives,” he tweeted.

The people cited above said more than 20 countries from around the world have sought supplies of hydroxychloroquine from India. The new partial easing of the ban will offer a way out in coping with this situation, but only after ensuring there are adequate supplies to meet domestic needs, the people said.

The Indian Council of Medical Research (ICMR) has said: “Hydroxychloroquine is found to be effective against coronavirus in laboratory studies and in-vivo studies. Its use in prophylaxis is derived from available evidence of benefit as treatment and supported by pre-clinical data.”

India’s national taskforce for Covid-19 has recommended the use of hydroxychloroquine for infections among “asymptomatic healthcare workers involved in the care of suspected or confirmed cases of Covid-19” and “asymptomatic household contacts of laboratory confirmed cases”.