The supreme court of Virginia on Friday ruled in favor of a prominent climate scientist, blocking a two-year bid by state officials to get access to his university emails and grant materials.

The case was brought by state attorney general Ken Cuccinelli, a skeptic of global warming, against the University of Virginia where well known climate scientist Michael Mann taught from 1999 to 2005.

Cuccinelli had tried to obtain Mann's communications relating to grants he received to conduct climate science research, alleging there may have been data manipulated to show a rise in global temperatures linked to fossil fuel use.

The attorney general sought the information -- which would have included research drafts, handwritten notes and emails -- via what is known as a "civil investigative demand" under the state's Fraud Against Taxpayers Act.

But the Virginia supreme court came down on the university's side, saying Cuccinelli's bid had no legal standing because the university was neither a "person" nor a "corporation" under the act and therefore could not be probed.

Also, Cuccinelli "did not sufficiently state what the attorney general suspected Dr. Mann did that was 'false or fraudulent,'" the ruling said.

The Union of Concerned Scientists hailed the ruling and said Cuccinelli was part of a "small but vocal minority in a pointless and costly investigation."

"We applaud the high court for reaffirming that Mr Cuccinelli didn't have a legal leg to stand on in his pursuit of Mann's and other scientists' private correspondence," said Michael Halpern, program manager for the UCS scientific integrity program.

"The university should be commended for its courage in standing up to the attorney general to ensure Virginia will remain a safe place for scientific research, even when elected officials don't like the results."

A lower circuit court judge had set aside Cuccinelli's request in 2010, ruling the attorney general had failed to provide evidence of wrongdoing by Mann or his colleagues.

Mann, who is now director of Pennsylvania State University's Earth System Science Center, was among the scientists whose emails were leaked in the 2009 "Climategate" scandal after the University of East Anglia's Climatic Research Unit's servers were hacked.

"I'm pleased that this particular episode is over," Mann said in a statement.

"It's sad, though, that so much money and resources had to be wasted on Cuccinelli's witch hunt against me and the University of Virginia, when it could have been invested, for example, in measures to protect Virginia's coast line from the damaging effects of sea level rise it is already seeing."

Mann also noted that a National Science Foundation investigation last year found no evidence of wrongdoing and no basis to the allegations against him by Cuccinelli and other climate change skeptics.

Cuccinelli said he would abandon the sole remaining case that is still pending in the matter, in keeping with the high court's decision.

"From the beginning, we have said that we were simply trying to review documents that are unquestionably state property to determine whether or not fraud had been committed," Cuccinelli said in a statement.

"Today, the court effectively held that state agencies do not have to provide state-owned property to state investigators looking into potential fraud involving government funds."