Evan Gershkovich, the American reporter Russia accuses of spying, appeals the extension of his detention.

Evan Gershkovich, the Wall Street Journal reporter jailed in Russia on espionage charges, appealed a court decision earlier this week that extended his detention by more than three months, The Journal confirmed on Friday.

Gershkovich, 31, had already spent almost two months in Moscow’s Lefortovo prison, known for its harsh conditions, when a court on Tuesday extended his detention until August 30. While the decision was expected by many, The Journal said in a statement at the time that he was “deeply disappointed” and would continue to demand his immediate release. The appeal was filed on Thursday, The Journal said.

The White House has said that Mr. Gershkovich is “unfairly detained”, which in effect means that the United States considers him a political prisoner. Russia has so far provided no evidence to support the spying charges, and the United States, The Journal and various press freedom groups have vehemently rejected them as false.

Mr. Gershkovich’s parents, Ella Milman and Mikhail Gershkovich, were admitted to the court building on Tuesday and were able to see their son for the first time since he was arrested on March 29, while on an informational tour in the city of Yekaterinburg in central Russia. Ms. Milman wore a button emblazoned with the phrase “Free Evan,” a rallying cry of the campaign for his release.