Chinese physicists have made a key breakthrough in a mystery left unsolved by two Nobel Prize winners, but they say any mention of a prize for their work is premature.

On Thursday, scientists announced in Beijing that they can finally answer the long-standing question of how one kind of neutrino changes into another.

"This is a new type of neutrino oscillation. Our precise measurements will complete the understanding of neutrino oscillation and pave the way for future understanding of the mystery of the universe," said Wang Yifang, a researcher at China's Institute of High Energy Physics (IHEP) and Chinese project manager of the Daya Bay experiment.

More than 100 scientists from China, US, Russia and other countries and regions conducted the research between Dec 24, 2011 and Feb 17, in an underground laboratory located close to the Daya Bay Reactor in Guangdong province.

Physicists believe the neutrino is the elementary particle of all materials. They have found three different kinds of neutrino, each of which has the ability to change into another.

Japanese scientist Masatoshi Koshiba and American physicist and chemist Raymond Davis Jr. discovered two of the ways in which neutrinos change, and both of them won the Nobel Prize. Now the Chinese scientists say they have found a third way.

However, when asked if their research might bring a Nobel Prize to China, Chen Hesheng, a researcher at the IHEP, demurred.

"This new finding is only the start of a long-term project, which will be conducted for decades by scientists all around the globe," Chen said.

"This is also an achievement for international cooperation," he added. " I'd like to say that we still have a long way to go."