Canada, Britain, France, Germany and the United States pledged on Thursday to work to disrupt “the hostile activities of foreign intelligence networks” and called on Russia to disclose its nerve agent program.

In a joint statement, the countries said they backed Britain’s assessment that Russian officers were behind a nerve agent attack on a former Russian spy and his daughter using Novichok after London charged two Russians in absentia.

“We have full confidence in the British assessment that the two suspects were officers from the Russian military intelligence service, also known as the GRU, and that this operation was almost certainly approved at a senior government level,” the statement said, adding that the countries urged Russia to provide “full disclosure of its Novichok program.”

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“Yesterday’s announcement further strengthens our intent to continue to disrupt together the hostile activities of foreign intelligence networks on our territories, uphold the prohibition of chemical weapons, protect our citizens and defend ourselves from all forms of malign state activity directed against us and our societies.”

Meanwhile on Thursday, Kremlin rejected that Russian President Vladimir Putin is ultimately responsible for poisoning Sergei Skripal in England, and said Russia is not going to investigate the suspects.

Britain’s security minister on Thursday called out Putin over the nerve agent attack targetingSkripal and his daughter and also warned that the U.K. would counter Russian “malign activity” with both public and covert measures.

Ben Wallace told the BBC that Putin and his government “controls, funds and directs” the military intelligence unit known as the GRU , which Britain believes used the Soviet-developed Novichok nerve agent to try to kill ex-Russian spy Skripal.

Skripal and his daughter Yulia were hospitalized for weeks in critical condition after they were exposed to Novichok in the city of Salisbury on March 4. They are now recovering in a secret location for their own protection.

Local woman Dawn Sturgess died and her boyfriend Charlie Rowley was sickened after they came across remnants of the poison in a discarded perfume bottle in June.

Britain on Wednesday announced charges in absentia against two alleged Russian agents, Alexander Petrov and Ruslan Boshirov — names that are likely aliases. The murder attempt was approved “at a senior level of the Russian state,” British Prime Minister Theresa May said Wednesday.

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Moscow strongly denies involvement in the attack, and Russian officials said they didn’t recognize the suspects.

Speaking to reporters on Thursday, Putin’s spokesman, Dmitry Peskov, called the accusations levelled against Putin and the Russian government “unacceptable.”

“Neither the Russian leadership nor its representatives have anything to do with the events in Salisbury,” he said.

Peskov also said that Russia “has no reasons” to investigate the two individuals charged on Wednesday because Britain has not asked for legal assistance in the case.

Britain has said it is not going to seek the men’s extradition because Russian law does not allow for the extradition of its nationals to be tried abroad.

Russian officials have been vehemently denying the fresh accusations. Foreign Ministry spokeswoman Maria Zakharova went on national television Wednesday evening, claiming that the security camera footage of the two suspects arriving at Gatwick Airport released by the British authorities has been doctored because it shows them at the same time in the same place. A closer look, however, shows that the men were walking in different gate corridors.

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Zakharova on Thursday accused Britain of “concealing the evidence,” and demanded that Britain share the suspects’ fingerprints and other data.

The Skripals’ poisoning ignited a diplomatic confrontation in which hundreds of envoys were expelled by both Russia and Western nations. But there is limited appetite among Britain’s European allies for further sanctions against Moscow.

Sergei Skripal’s niece, Viktoria, on Thursday called on British authorities to allow her to visit her family in Britain after her visa application was denied.

She said that she does not know the men Britain suspects of being behind the poisoning.

Skripal also said that she doubts that the former Russians spy is still alive because he has not communicated with the family since the poisoning.

Britain plans to press its case against Russia at the U.N. Security Council later on Thursday.

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With files from Reuters