Health minister Anbumani Ramadoss has said that the government is "very concerned" over Swiss drug multinational Novartis AG''s challenge to Indian patent laws that seek to restrict the global supply of cheap anti-AIDS drugs.

Novartis has filed a petition in the Madras High Court in Chennai against Indian patent laws that do not allow the patenting of minor improvements to known molecules, arguing that Indian the patent system stifles innovation and that a tightening of intellectual property laws would increase investment for developing more drugs.

Asked if an adverse outcome of the court case could affect the supply of affordable anti-AIDS drugs from India, Ramadoss told reporters in New Delhi, "We urge Novartis to desist from this and withdraw from this."

The health minister warned that the government may be forced to overrule patents and resort to compulsory licensing to produce vital drugs in the public interest, if it was forced to do so.

He said so far the India had refrained from compulsory licensing, but it should not be forced to do so.

Last week, a two-judge bench of the Madras High Court reserved its verdict on the Novartis challenge against the Indian patent system, and also turned down an appeal against the rejection of a petition turning down patent cover for its anti-cancer drug Glivec.

The application was rejected because the drug was a new form of a known substance.

Humanitarian groups have been vociferous in their criticism of the Swiss drug maker''s attempt to protect its profits over the wider needs of poor HIV / Aids patients, particularly the sub-Sharan African countries.