His allegation follows the latest round of negotiations on whaling which saw Togo join the commission by paying A$10,000 in cash at the door of the conference.
"I think that some of the practices within the IWC over many years could be called corrupt," Senator Campbell told ABC radio.
"These sorts of practices have been going on for many years and I think the fact that there is now a very significant international spotlight being shone back on the IWC ... is a particularly good thing for the organisation because it needed a spotlight shone on it," Mr Campbell said.
Japan won its first vote at the commission in 20 years, an endorsement of Japan's pro-whaling position.
Senator Campbell said the Japanese win would eventually be a win for conservation forces because more nations would become involved in the IWC and vote with the anti-whaling nations, including
Australia.
"The motion that was won was a pious motion of no affect," Senator Campbell said.
Japan is seeking to overturn the moratorium against commercial whaling but needs a vote of 75 percent of the IWC delegates in favour to lift the edict.
Protesters fined
Meanwhile a magistrate has fined six Greenpeace activists more than A$12,000 a day after their seaborne protest at the world whaling talks in the Caribbean state of St Kitts and Nevis.
Five activists who jumped from high-speed launches and waded through the surf to the beach of the resort hosting the talks were convicted of illegal entry and fined A$2,500 each.
The protesters, four from Brazil and one from Mexico, had boarded the launches from the nearby Greenpeace ship Arctic Sunrise, which had been banned from entering St Kitts' port, during International Whaling Commission talks.
They had planned to plant more than 800 banners in the sand in the shape of whale fins bearing the slogan "R.I.P." in memory of whales killed by Japan in the Southern Ocean during its "research whaling" program this year.
A sixth activist, Greenpeace spokesman Mike Townsley from Britain, was convicted of obstructing a police officer and fined about A$500.
Prosecutors said Townsley was charged after telling other protestors not to give their names to a senior police officer. A second charge of resisting arrest was dropped against him.
All six activists were remanded in custody until the fines were paid, an issue complicated by an unscheduled public holiday in St Kitts to celebrate the island's first ever Test cricket match, between India and the West Indies.
They were then to be turned over to immigration authorities until they leave the country.
Four other activists also arrested on Tuesday, but who had entered the country legally, were released without charge on Wednesday.