"Russia will continue demanding that British authorities provide detailed information about the incident, grant consular access to the Russian citizens and begin a joint investigation," the embassy said.
"The document stresses that London has blatantly violated international rules by ignoring Russia’s vested right to obtain information on its citizens who have been held in isolation … at an undisclosed location," the embassy added.
The former Russian spy and his daughter were found slumped on a bench in a park on March 4 after being exposed to a suspected nerve agent of the Novichok type. UK authorities accused Russia of being behind the murder attempt, a claim rejected by Moscow as baseless.
READ MORE: Travel Advice: Abridged Sightseeing Guide to Salisbury (PHOTOS)