"The simple reality is that Russia has committed an attack on British soil which has seen the death of a British citizen," Williamson said on Monday.
"That is something that I think the world will unite with us in actually condemning," he added.
Police have said Sturgess handled an item contaminated by Novichok, a few miles from where Russian double agent Sergei Skripal and his daughter Yulia were attacked with the same poison in March.
It was unclear if Williamson was referring to the attack on the Skripals or a new attack. Britain has blamed Russia for the poisoning of the Skripals, but Russia has denied involvement.
Earlier on Monday, Britain’s top counter-terrorism officer said detectives were unable to say if the Novichok that poisoned Sturgess and a man who is in critical condition in hospital was from the same batch that struck down the Skripals.
As reported, Russian ex-spy Sergei Skripal, 66, and daughter Yulia Skripal, 33, remain critically ill in hospital, after they were found unconscious on a bench in the Wiltshire city on March 4. The UK government says they were poisoned with a nerve agent of a type developed by Russia called Novichok and PM Theresa May said she believed Moscow was "culpable."
UK expelled 23 Russian diplomats as part of a "full and robust" response – prompting Russia's Foreign Minister Sergei Lavrov to say it will "certainly" expel British diplomats in response.
On March 16, Nato Secretary General Jens Stoltenberg said the alliance had "no reason to doubt the findings and assessments by the British government" which suggested Russian responsibility. He said the "UK is not alone" and Nato allies gave "strong political support" to Britain, following a joint statement from the US, France and Germany backing Mrs May's government and a pledge of support from Australia.
British Foreign Minister Boris Johnson said that the U.K.'s government believes that it was likely Putin's decision to direct the use of a nerve agent on the streets of the U.K.
On March 26, U.S. President Donald Trump ordered the expulsion of 60 Russians from the United States, including 12 people identified as Russian intelligence officers who have been stationed at the United Nations in New York.