London, Mar 20 (PTI) Nearly two dozen Russian diplomats expelled by the British government in retaliation over the poisoning of a UK-based former Russian double agent and his daughter left the country today with their families.

The Russian Embassy in London confirmed that around 80 people, including the 23 Russian diplomats and their families, were on their way back to Moscow, which marks the one-week deadline given by British Prime Minister Theresa May in her House of Commons statement last week.

May told Parliament that the UK was certain that a deadly nerve agent from the Novichok stock associated with Russia had been used in the attempted murder of Sergei Skripal and his daughter Yulia in Salisbury on March 4.

The 23 diplomats expelled were identified by May as “undeclared intelligence officers”, a charge the Russian embassy has denied.

A small crowd gathered outside the embassy and waved goodbye to people carrying suitcases, children and pets as they boarded diplomatic cars and buses. They boarded their flight back to Russia from Stansted Airport.

The Kremlin has also expelled 23 British diplomats in response, who have until Saturday to leave Russia.

Among other sanctions, Russia announced the closure of both the British Council in Russia, which promotes cultural ties between the nations, and the consulate in St Petersburg.

Tensions between Britain and Russia, which categorically denies any involvement in the Skripals’ poisoning, are expected to continue to heighten as May considers further action after a meeting of the National Security Council (NSC) later today.

Meanwhile, Britain’s senior-most counter-terrorism officer, Scotland Yard Assistant Commissioner Neil Basu, confirmed that investigations into the Salisbury nerve agent attack could take months.

“To date, detectives have recovered 762 exhibits and are trawling through around 4,000 hours of CCTV We are learning more about Sergei and Yulia’s movements but we need to be clearer around their exact movements,” the Metropolitan Police counter-terrorism chief said.

Skripal, a 66-year-old retired military intelligence colonel, came to the UK in 2010 after being released from prison in Russia and was granted political asylum.

He had been jailed in Moscow in 2006 for spying for Britain and passing the identities of Russian secret agents in Europe to MI6, the UK’s Secret Intelligence Service.

His 33-year-old daughter Yulia flew into the UK from Russia on March 3, the day before she and her father were found slumped on a bench near The Maltings shopping centre in Salisbury, Wiltshire.

Britain continues its mission to build international support on the issue, with the latest phone call taking place between Japanese Prime Minister Shinzo Abe and May today.

Downing Street said Japan condemned the Salisbury attack and “shared our outrage”.

The leaders of France, Germany and the US have already pledged support for the UK in a joint statement and the European Union (EU) has offered its “unqualified solidarity”.

The EU leaders will meet at a summit in Brussels on Thursday to discuss any potential response to Russia.

This is published unedited from the PTI feed.