Drug patents in India are an important issue as many countries depend on generic drugmakers to make and sell cheaper versions of critical drugs to them. Gilead's three patents in India for remdesivir stem from 2009 when the drug was in development to treat Ebola.

Remdesivir is the only drug approved to treat COVID-19 patients after promising early trial results prompted US regulators to grant emergency use authorisation on May 2. To expand its access, Gilead said this week it had signed non-exclusive licensing pacts https://in.reuters.com/article/us-health-coronavirus-gilead-sciences/gilead-ties-up-with-generic-drugmakers-for-covid-19-drug-supply-idINKBN22O2HJ with five generic drugmakers based in India and Pakistan, allowing them make and sell remdesivir for 127 countries.

But health access groups say the pacts mean cheaper forms of the drug may not become available in nations seen as non-profitable to the five drugmakers.

"The licenses divide the global market into two and profitable markets are retained with Gilead and less profitable markets are given to the five generic companies," said K. Gopakumar, senior legal researcher at Third World Network, which sent a letter to the Indian government on Wednesday.

The letter by Third World Network, a Malaysia-based non-profit group, followed a similar appeal by India's Cancer Patients Aid Association last week.

The aid group Doctors Without Borders has also opposed Gilead's patents on remdesivir, saying such licensing pacts are "not acceptable" amid a global health emergency.

Gilead's patents on remdesivir in India allow it to exclusively make and sell the drug in the country until 2035 unless it licenses those rights out.

Gilead's India spokeswoman and India's commerce and health ministries did not immediately respond to emails seeking comment.

India's Cancer Patients Aid Association said it might pursue legal action, noting that cancer patients have compromised immunity and are highly susceptible to the virus.

"It is imperative at a time like this that no monopoly rights be granted, so that more manufacturers can produce the drug to be made available to all the people who need it, at affordable costs," it said.

Except for remdesivir, there are currently no other drugs or vaccines approved to fight coronavirus, which has killed more than 200,000 people globally.