The Kremlin said on Thursday it had offered Britain its assistance in investigating a nerve agent attack on a Russian former spy and his daughter in Salisbury in March long ago, but had been rebuffed.
The Kremlin was commenting on remarks by British Security Minister Ben Wallace who earlier on Thursday called on Moscow to give details about the original Novichok nerve agent attack after two British citizens were struck down with the same poison.
Moscow denies any involvement in the original attack on Sergei Skripal and his daughter Yulia and has cast allegations of Russian involvement as part of a sophisticated plot to damage its reputation and hosting of the football World Cup.
The Kremlin said on Thursday that Russia had long been ready to help Britain get to the bottom of what really happened to the Skripals but complained it had been ignored.
"To my shame I don't know who Ben Wallace is," Kremlin spokesman Dmitry Peskov told reporters on a conference call when asked about the British minister's call for Russian help.
"(But) the minister knows very well that Russia proposed a joint investigation long ago and that this proposal was on the agenda. It was made long ago and unfortunately the British side is not showing any interest in such proposals."
Peskov said the Kremlin was worried by the latest news from Britain and hoped the two Britons in a critical condition would recover.
He said he was unaware of any official British requests to Russia for help in relation to the investigation into the new incident and said the Kremlin was concerned by reports that a nerve agent had once again been used on European soil.