Karabatic and Honrubia, a former Montpellier player now at Paris St Germain, were arrested on Sunday following a French league game between their two clubs in Paris.
Karabatic along with his brother Luka and Honrubia were among 15 people being heard in Montpellier by judges Thomas Meindl and Marie-Christine Desplat-Didier.
"Nikola and Luka have been placed under formal investigation," their lawyer Michael Corbier told reporters.
Honrubia's lawyer Patrick Maisonneuve added: "He denies this charge. He admits to betting, but it's not a criminal offence."
Karabatic led France to back-to-back Olympic titles in 2008 and this year while Honrubia also won gold in London.
Prosecutor Brice Robin alleges that a total of 87,880 euros ($113,400) of bets were placed on a first division game between Montpellier and Cesson-Sevigne last May - 40 times the usual amount for this kind of match.
Most of the bets were placed around the same time of day and 99.94 percent were placed on struggling Cesson-Sevigne to lead at halftime, he added.
Robin said the investigation was focused on the players and their relatives, with both clubs' chairmen and coaches having been cleared of any suspicion of wrongdoing.