A senior Russian official said on Wednesday that the United States' designation of Wall Street Journal reporter Evan Gershkovich as “wrongfully detained” meant nothing to Russia and would not change its approach to his case, the TASS news agency reported.

Russia's FSB security agency arrested Gershkovich, a U.S. citizen, at the end of March and has charged him with espionage charges that carry a maximum 20-year prison sentence.

His arrest brought an outcry from the Wall Street Journal, U.S. President Joe Biden, other media organisations and rights groups.

A Moscow court next week will hear an appeal by Gershkovich's legal team against a ruling that he be held in pre-trial detention at Moscow's Lefortovo prison until at least May 29.

Deputy Foreign Minister Sergei Ryabkov said Russia was currently considering granting U.S. diplomats consular access to Gershkovich, who has so far had only minimal contact with his legal team since his detention two weeks ago. But he criticised U.S. attempts to“pressure” Moscow over the issue.

"We will not tolerate any attempts to pressure us, and it has no significance what status they assign to this person in Washington. We will act in accordance with our own internal needs, norms and laws that apply in this situation, and nothing more,” TASS quoted Ryabkov as saying.

Biden spoke to Gershkovich's family by telephone on Tuesday and said Washington was doing “everything in its power” to secure Gershkovich's release. He is the first American reporter jailed in Russia on espionage charges since the end of the Cold War.

Russia has not granted U.S. consular officials access to Wall Street Journal reporter Evan Gershkovich since he was detained late last month and is in violation of international law, State Department deputy spokesperson Vedant Patel said on Monday.

Patel told reporters at a regular press briefing that Moscow had over the weekend formally notified Washington of the detention, but the United States is still seeking consular access to Gershkovich, who has been detained since March 29 on espionage charges.

"At this point it is a violation of Russia's obligations under our consular convention and a violation against international law,” Patel said. The United States and the Soviet Union agreed in a treaty signed in 1964 that a consular officer shall be allowed to visit a detained or arrested citizen of the other state within two to four days of detention depending on their location.

"We have stressed the need for the Russian government to provide this access as soon as possible,” Patel added.

The Russian embassy in Washington did not immediately respond to a request for comment. Lawyers for the Wall Street Journal have visited the journalist, and the newspaper has called for his immediate release.

The United States has called for Russia to release Gershkovich and dismissed claims of espionage as ridiculous.