Evgeny Vitishko stands in front of the new road between Adler and Krasnaya Polyana in the Black Sea resort of Sochi. (Mikhail Mordasov/AFP/Getty Images)

European Union officials and the International Olympic Committee pressed Russia on Thursday to explain why a local activist who has been investigating the environmental impact of the Winter Games has been sent to prison for three years.

Evgeny Vitishko and a fellow activist were convicted in 2012 of damaging a fence in a forest near the regional capital of Krasnodar. Both denied the charges — they said they were investigating the construction of a country house for the governor of Krasnodar that was damaging a protected forest. Both were given suspended sentences of three years in a labor camp.

But on Wednesday, a judge ordered Vitishko to serve his sentence, upholding an earlier decision that he had violated the terms of his parole because of a curfew infringement.

The decision came as Vitishko and his organization, Environmental Watch of the North Caucasus, were planning to issue a report on the effects of Olympic construction in Sochi.

In a statement Thursday, the Delegation of the European Union to Russia said it was concerned by the imprisonment order.

“This sentence appears disproportionate and seems aimed at preventing Mr. Vitishko from presenting his report on the environmental impact of the Olympic Games,” the statement said.

“We reiterate the priority we attach to Russia respecting its international human rights commitments on freedom of assembly, expression and association, before, during and after the Sochi games.”

In Sochi, Mark Adams, a spokesman for the International Olympic Committee, said the IOC had asked the Sochi Olympic Organizing Committee to raise the issue with Russian authorities and report back with an explanation of the decision to send Vitishko to prison.

Human Rights Watch and other organizations have called the prosecution politically motivated.

Vitishko, a 40-year-old geologist, and another environmentalist, Suren Gazaryan, were found guilty of causing $4,000 damage to a fence by spray-painting a slogan on it and opening a hole in it. They denied the charge and accused officials of trying to prevent them from drawing attention to what was behind the fence — a lavish country house that they said was being constructed illegally for the governor. The governor has denied owning the house.

Later in 2012, Gazaryan, an expert on bats and a member of the Russian Academy of Sciences, was called in for questioning after guards confronted him as he walked near a Sochi compound believed to belong to President Vladimir Putin. He fled the country, fearing he would be sent to prison for parole violation.