Ships not allowed to use their wireless telegraph devices in several Russian harbours according to the Secret Admiralty Weekly Intelligence Summary Nr. 31 for the week ending 6 August 1921

An item reported that the Soviet government decided that in the harbors of Petrograd, Kronstadt, Murmansk, Archangel, Odessa (Ukraine), Novorossisk, Tuapse, Nikolseff, Feodosia (Crimea) and Sevastopol (Crimea) ships were not allowed to use their w/t equipment.

Source

The National Archives CAB-24-127-7. No.31. Weekly appreciation of matters of naval interest for the week ended 6 August 1921