Thieves have stolen jewelry worth 1 million Swiss francs (about U.S. $825,000) from the world's biggest and most luxurious watch and jewelry fair in Basel, authorities said Saturday.

"It happened on Tuesday before the fair started," said Peter Gill, spokesman for the public prosecutor's office in the canton, or state, of Basel.

The jewelry was grabbed when it was being brought to a stall in the exhibition hall for the Baselworld fair, he told The Associated Press.

"Nobody was hurt," he added.

He declined to comment further to avoid compromising the ongoing inquiry.

The theft is likely to be the largest in the fair's recent history, Baselworld spokesman Bernhard Keller told the AP.

But he said that security at the fair was adequate.

"We have very good security measures. There is no need to change anything," he said, adding that the show was continuing normally.

More than 2,000 exhibitors from 45 countries present the latest products from diamond encrusted masterpieces to modest plastic models at the fair, which runs from April 12 to 19.