India's top court denied Monday a patent request by Swiss drug giant Novartis in a landmark ruling that activists say will protect access to cheap generic versions of drugs in developing nations.

The Supreme Court ruled that the compound for a new version of its blockbuster cancer drug Glivec, for which Novartis was seeking a patent, "did not satisfy the test of novelty or inventiveness" required by Indian law.

The judgement capped a seven-year legal battle by Novartis to win protection for the drug that went to the heart of India's patent law.

Lawyer Anand Grover, representing Cancer Patients Aid Association, said he was "ecstatic with the ruling".

"This will go a long way in providing affordable medicine for the poor," Grover said outside the courtroom in New Delhi.

The case was the most high-profile of several patent battles being waged in India and was seen as having far-reaching implications in defining the extent of patent protection for multinational drug firms operating in the lucrative market.

Novartis had argued that its updated form of Glivec merited a patent, saying that it was a significant improvement from the earlier version because it is more easily absorbed by the body.

But critics described the changes in Glivec -- often hailed as a "silver bullet" for its breakthrough in treating a deadly form of leukaemia -- as "an obvious, routine modification".

India currently allows patents only for new drugs or for an updated version of a drug that displays "enhanced" therapeutic efficiency.