India is likely to add more HIV/AIDS and tuberculosis drugs to its list of essential medicines that are subject to price caps, people directly involved in the process said, in a move to improve affordability of drugs to treat the deadly diseases.

All the drugs on the government's HIV/AIDS and TB control programs are likely to be added in the list, the people said.

India provides a number of key HIV/AIDS and TB medicines for free under the government's disease control programs through state-run clinics and distribution centers.

But many patients, particularly those with TB, prefer more expensive private clinics as treatment is widely considered of higher quality. The private sector accounts for about 80 percent of India's healthcare delivery market.

India has about 2.2 million TB patients, the highest in the world, and an estimated 2.1 million are afflicted with HIV/AIDS.

The additional HIV/AIDS and TB medicines would join a list of nearly 400 essential drugs under price control in India, where more than 70 percent of people live on under $2 a day and health insurance is scarce.

The revised list of essential medicines could be announced in the next six months, said four members of a health ministry panel that was set up to review the list that was last revised in 2011.

The people, who declined to name the medicines that could be added, did not want to be identified as the additions have not been finalised.

Y.K. Gupta, vice chairman of the panel, declined to comment on new drugs that would be part of the list and said the discussions were ongoing.

"We are reviewing drugs across therapy areas, and there could be additions as well as deletions to the 2011 list," said Gupta. "We will have better clarity on when the list could be out by the end of April."

Indian drugmakers Cipla Ltd, privately held Emcure Pharmaceuticals Ltd and Hetero Healthcare Ltd are among the major companies selling HIV/AIDS drugs in India.

TB drugs are sold by domestic firms such as Lupin Ltd, Cadila Healthcare Ltd, as well as foreign firms such as Sanofi SA, Pfizer Inc and Novartis AG.

Some firms could stop making the drugs if they feel the drug prices are capped too low, said S. Srinivasan, a health activist with All India Drug Action Network, a group of non-profit organizations working to improve access to essential medicines.

"The aim is to improve affordability, but the effect of price control is unpredictable," Srinivasan said.