“The ball is in the court of the United States. We are waiting for them to respond to the ideas that were presented to them,” Sergei Ryabkov, the deputy foreign minister, told Russia’s state TASS news agency in an interview.

“They are well known to the relevant parts of the US administration. I understand that, perhaps, something in these ideas does not suit the Americans. That’s their problem,” he added.

“We consider our approaches to be fully justified, sensible, balanced. We expect that this is how they will view them.”

Mr Gershkovich is set to face a closed-door trial in the Urals city of Yekaterinburg on June 26 and could face up to 20 years in prison if found guilty.

American soldier jailed 

Mr Ryabkov’s comments came as a court in Russia’s far east jailed a US soldier for three years and nine months, allegedly for threatening to kill his girlfriend and stealing from her.

Staff Sergeant Gordon Black, 34, was arrested last month in the far eastern city of Vladivostok, where he was visiting a Russian woman he met and dated while serving in South Korea.

The woman, named by Russian media as Aleksandra Vashchuk, accused Sgt Black of stealing about 10,000 roubles ($120) from her and said she had been physically attacked.

Sgt Black pleaded “partially guilty” to theft and not guilty to threatening to kill Ms Vashchuk, Russian media reported.

His lawyer intends to appeal the verdict, the TASS news agency reported.

Washington has accused Moscow of arresting its citizens on baseless charges to use them as bargaining chips to secure the release of Russians convicted abroad.