UK Security Minister, Ben Wallace says Russian President, Vladimir Putin must take responsibility for the Salisbury Novichok attack.
Speaking to reporters, Mr Wallace said “ultimately, of course”, Russia’s president was behind the poisoning.
The Kremlin, which denies involvement, said it was “unacceptable” to make accusations against the leadership.
The UK has named two men believed to be from Russia’s military intelligence service, the GRU, as the main suspects in the attack.
Ex-Russian spy Sergei Skripal, 66, and his daughter Yulia, 33, were poisoned with Novichok on March 4. Det Sgt Nick Bailey also fell ill after responding to the incident.
Police have linked the attack to a separate Novichok poisoning on June 30, which led to the death of Dawn Sturgess.
Prosecutors say there is sufficient evidence to charge the two men, and UK officials are due to brief the UN Security Council on the investigation.
Theresa May told the Commons on Wednesday that the suspects had entered the UK on Russian passports using the names Alexander Petrov and Ruslan Boshirov.
She said the poisoning was “not a rogue operation” and was “almost certainly” approved at a senior level of the Russian state.
UN Security Council meeting
Britain called Thursday’s meeting of the UN Security Council of which Russia is a permanent member, along with UK allies the US and France.
Mr Wallace said the UK must use the meeting to “maintain the pressure, to say the behaviour we have seen is totally unacceptable”.
He said Mr Putin’s government “controls, funds and directs the military intelligence, that’s the GRU”, adding that nobody could say the Russian leader was “not in control of his state”.
BBC security correspondent Gordon Corera said that alongside the meeting, it was thought there would be less visible activity including covert work by British intelligence to disrupt the GRU.
Mrs May has also said Britain will push for the EU to agree new sanctions against Russia.
Ahead of the UN meeting, Australia said it was “in lock step with the UK on the importance of holding Russia to account” over the “dangerous and deliberate act”.
Police are asking the public for information about a suitcase seen in the CCTV image of the two suspects leaving Heathrow Airport on Sunday 4 March.
In the image, Mr Petrov can be seen pushing a hard dark-coloured wheelie suitcase with a green stripe of the size that can fit into hand luggage lockers.
It does not appear that he arrived in the country with the suitcase.
Counter terrorism officers are also interested in any information the public can give them about the grey and olive backpack that Mr Petrov and Mr Boshirov were both seen wearing at different times on Sunday.