The MP for Great Yarmouth has said "Russia will the price" for its "merciless aggression" towards Ukraine.
On Thursday Russia president Vladimir Putin announced a "special military operation" in the country's Donbas region which has sparked global response..
Mr Lewis, who is also Secretary of State for Northern Ireland said: "The Russian invasion of Ukraine is a horrifying and completely unjustifiable attack on the sovereignty and territorial integrity of Ukraine and its people.
"Russia will pay the price for such unprovoked and merciless aggression.
"My thoughts are with the people of Ukraine."
Mr Lewis also defended accepting £48,000 in donations from wealthy individuals with links to Russia and President Vladimir Putin in October 2020.
He received £25,000 from Lubov Chernukhin, a banker and wife of Mr Putin’s former deputy finance minister, and £23,000 from Alexander Temerko, a former chief of a Russian arms company.
Mr Lewis said on Thursday: "Our electoral rules, as set out by the independent Electoral Commission, are clear.
"Financial contributions can only be received from a permissible source determined by law. A permissible source is either an individual registered on a UK electoral register or a UK registered company.
"I have always complied with these legal requirements and statutory reporting of received donations.
"All my donations are properly and transparently declared to the Electoral Commission, published by them, and comply fully with the law.”
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