Tokyo, Japan (CNN) -- A court in northern Japan found two Greenpeace activists guilty Monday for stealing whale meat, but suspended their sentences, Greenpeace Japan said.
The Aomori District Court ruled that the activists, Junichi Sato and Toru Suzuki, will only have to serve one-year terms if they commit a crime in the next three years, Greenpeace said.
In a press conference after the verdict, Sato said Greenpeace would appeal the case. He said Monday's sentence was "unfair" and "preventing the citizens' right to know."
Suzuki said in a statement that the sentence was disproportionate and undeserved.
"We set out to reveal the truth about the government's whaling program, but instead have been punished, while those behind the misuse of public money walk free," he said.
The case highlights rising tensions between anti-whaling activists and Japanese officials.
Japan's whaling has drawn sharp criticism from environmental advocacy groups, who claim it involves the cruel slaughter of whales so that meat can be sold in markets and restaurants.
Japanese officials say their hunts are permitted under rules that prohibit commercial whaling but allow whaling for scientific reasons.
Greenpeace has said a tip led Sato and Suzuki to a whaling ship smuggling the whale meat onto the black market.
In a press conference, Sato announced that they had found 23 kilograms (50.7 lbs) of whale meat in a box they intercepted. He showed the whale meat in the box, and alleged a systematic, large-scale embezzlement within Japan's whaling program.
Greenpeace delivered the whale meat to the Tokyo prosecutor's office days later.
The police moved, but not on the Greenpeace allegations.
"They dropped the case and we are the ones who got arrested," Sato said in an interview earlier this year.
Sato and Suzuki were arrested in June 2008 and charged with trespassing and theft. They faced up to 10 years behind bars.
Regardless of the reason, police said, it was theft because Greenpeace admitted that it intercepted the box.
Reaction outside of Japan was swift.
Protests were held around the world in support of the men, who came to be known as the "Tokyo Two."
And a U.N. human rights body declared Japan's trial of the men a violation of human rights.
Joji Morishita of the Japan Fisheries Agency has said the government recognizes the right of protest, but activists will be punished if they break Japan's laws.
But Greenpeace International's executive director, who traveled to Japan for the ruling, said Monday that the organization was determined to get the activists' "unjust" conviction overturned.
"Activists are not criminals, and to treat them as such has a chilling effect in society, undermining the quality of democracy," Executive Director Kumi Naidoo said in a statement after Monday's ruling.
In July, a Japanese court found Peter Bethune, an environmental activist from New Zealand, guilty on five charges, ranging from assault against whalers to trespassing into a whaling vessel.
He was given a two-year suspended prison sentence and five years' probation Wednesday by a Tokyo district court judge for throwing butyric acid at a whaling ship, jumping aboard and attempting to make a citizen's arrest of the captain.