India's Supreme Court on Monday rejected drug maker Novartis AG's right to patent a new version of a cancer drug in a landmark decision that healthcare activists say ensures the poor will get continued access to cheap, generic versions of lifesaving medicines.

Novartis had argued that it needed to new patent to protect its investment in the cancer drug Glivec while activists said the company was trying to use loopholes to make more money out of a drug whose patent had expired.

The cheap medicines produced by India's $26 billion generic drug industry are a lifeline for the poor in many developing countries.

The ruling sets a precedent that will prevent international pharmaceutical companies from obtaining fresh patents in India on updated versions of existing drugs, said Pratibha Singh, a lawyer for the Indian generic drug manufacturer Cipla.

The court ruled that a patent could only be given to a new drug, she told reporters outside the court.

"Patents will be given only for genuine inventions, and repetitive patents will not be given for minor tweaks to an existing drug," Singh said.

Novartis has fought a legal battle in India since 2006 for a fresh patent for its leukemia drug Gleevec, known in India and Europe as Glivec.

India's patent office had rejected the company's patent application because it was not a new medicine but an amended version of its earlier product.