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

Novartis had argued that it needed a 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 decision has global implications since India's $26 billion generic drug industry supplies much of the cheap medicine used in the developing world.

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, which makes a generic version of Glivec.

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 did not immediately return calls for comment.

The Swiss pharmaceutical giant 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. The patent authority cited a legal provision in India's 2005 patent law aimed at preventing companies from getting fresh patents for making only minor changes to existing medicines -- a practice known as "evergreening."

Novartis appealed, arguing Glivec was a newer, more easily absorbed version of the drug that qualified for a fresh patent.

Anand Grover, a lawyer for the Cancer Patients Aid Association, which has taken the lead in the legal fight against Novartis, said the ruling Monday prevented the watering down of India's patent laws.

"This is a very good day for cancer patients. It's the news we have been waiting for for seven long years," he said.

Aid groups, including Doctors Without Borders, have opposed Novartis' case, fearing that a victory for the Swiss drugmaker would limit access to important medicines for millions of poor people around the world.

Gleevec, used in treating chronic myeloid leukemia and some other cancers, costs about $2,600 a month. Its generic version was available in India for around $175 per month.

"The difference in price was huge. The generic version makes it affordable to so many more poor people, not just in India, but across the world," said Y.K. Sapru, of the Mumbai-based cancer patients association.