Russia on Saturday, March 17 announced it is expelling 23 British diplomats and threatened further measures in retaliation in a growing diplomatic dispute over a nerve agent attack on a former spy in Britain, The Associated Press reports.

The Russian Foreign Ministry also said in a statement that it is ordering the closure of the British Council, a government organization for cultural and scientific cooperation, and that it is ending an agreement to reopen the British consulate in St. Petersburg.

It ordered the diplomats to leave within a week.

The statement said the government could take further measures if Britain takes any more "unfriendly" moves toward Russia. British Ambassador Laurie Bristow was called to the Foreign Ministry Saturday morning to be informed of the moves.

British Prime Minister Theresa May this week expelled 23 Russian diplomats and severed high-level bilateral contacts over the March 4 poisoning of ex-spy Sergei Skripal and his daughter Yulia. They remain in critical condition in hospital.

Britain's foreign secretary accused Russian President Vladimir Putin of personally ordering the poisoning of the Skripals, who were found slumped on a public bench in the southern English city of Salisbury. Putin's spokesman denounced the claim.

While Russia has vigorously denied involvement in the attack, Western powers see it as the latest sign of alleged Russian meddling abroad. The tensions threaten to overshadow Putin's expected re-election Sunday for another six-year presidential term.