Skeipal and his daughter Yulia were found unconscious on a bench at a shopping center on Monday and still in a coma. They were believed to be hurt by a highly toxic chemical, according to Mark Rowley, an assistant commissioner who heads a counter-terrorism policing unit.
The Russian Embassy in Britain made a statement on Wednesday saying that Russia still has not received any further information on the incident from Britain, which is "rather worrying."
The statement also said that British Foreign Secretary Boris Johnson's recent speech is strongly anti-Russian and "looks more like an attempt to send the investigation upon a political track."
Johnson made a speech earlier this week, saying Britain "will respond robustly "if the attack is found to be the result of hostile activity by another government."
Russian presidential spokesman Dmitry Peskov said Russia had no information on the cause of the incident and that Moscow was open to cooperation.
Skripal, now 66, was sentenced in Russia in 2006 to 13 years in prison for cooperating with the British Secret Intelligence Service MI-6 and releasing names of Russian intelligence agents working undercover in Europe. In 2010, Skripal was pardoned by former Russian President Dmitry Medvedev and then moved to Britain.