International aid groups have strongly criticised a move by the lower house of India's parliament to pass a new patents law.
India has had a liberal approach to patented drug manufacture
It prevents domestic drug manufacturers from making low-cost generic copies of patented drugs.
Campaigners say the move will deprive millions of people around the world of access to cheap life-saving medicines.
India took the step to pass the bill in order to honour its commitment to the World Trade Organisation.
The bill will now go to the upper house of parliament and is expected to be approved into law.
Those opposing the bill say it will hurt hundreds of thousands of Aids and cancer patients across the world.
"Because India is one of the world's biggest producers of generic drugs, this law will have a severe knock-on effect on many developing countries which depend on imported generic drugs from India," said Samar Verma, regional policy adviser of British charity Oxfam.
The France-based Medecins Sans Frontieres (MSF) wrote a letter to Sonia Gandhi, president of India's governing Congress party, highlighting its concern.
"We are deeply disturbed and concerned that you are failing to listen to the voices of your people who have entrusted you with their welfare," it said.
But the Indian government says it has taken such concerns on board while preparing the bill.
"All safeguards have been put in the regime and the government will have enormous powers to deal with any unusual price rise," Commerce Minister Kamal Nath said.
The new legislation will replace the current patent law, which has allowed drug makers to copy patented drugs as long as they use a different manufacturing process.
This liberal approach has helped to foster a strong drug manufacturing industry in India for more than three decades.
However, the government argues that patent recognition is an essential pre-condition for India's drug industry to further its own drug research and development or attract foreign partners.