Olga Kharlan, a four-time Olympic fencing medalist, was disqualified from the World Fencing Championships in Milan on Thursday after refusing to shake hands with her Russian opponent.

After Ms. Kharlan defeated Anna Smirnova, a Russian competitor who had joined the competition with a neutral status, Ms. Smirnova extended her hand to Ms. Kharlan, who extended her saber instead. According to the sport’s rules, a fencing bout does not end until the two fencers have saluted each other and shaken hands, and the referee can penalize those who do not comply.

The Ukrainian Fencing Federation said on Thursday that Ms. Kharlan had “convincingly” won and would appeal the disqualification.

Several Ukrainian political officials condemned the disqualification, tying it directly to Russia’s invasion of Ukraine.

“Anna Smirnova lost the fair competition and decided to play dirty with the handshake show,” Dmytro Kuleba, Ukraine’s foreign minister, said on Twitter, adding that Ms. Smirnova’s conduct was exactly how the “Russian army acts on the battlefield.”

Ruslan Stefanchuk, the Ukrainian Speaker of Parliament, praised Ms. Kharlan on the Telegram messaging app, writing that not shaking hands “is a sophisticated form of just ignoring terrorists with no name, no honour, no flag under which they compete.”

Ms. Kharlan, 32, is among the world’s top fencers, having won a gold medal in the team saber competition at the 2008 Olympic Games in Beijing. Since then, she also has two bronze medals and a silver in Olympic competition.

Russia and Belarus were not invited by the International Olympic Committee to compete as nations in next year’s Summer Olympics in Paris. But it is possible that fencers from both countries will be able to participate as neutral athletes, without their national flags or anthems, so long as they meet certain requirements, such as not having shown public support for the invasion.

With war as a backdrop, drama in the sport has been playing out in the United States and elsewhere this summer. Three fencers who left Russia and denounced the invasion competed as neutral athletes at the United States summer championships earlier this month in Phoenix. This departure was so embarrassing to the Russians that it led to the firing of the country’s top épée coach.

On Wednesday, Igor Reizlin, a Ukrainian fencer, withdrew from his competition against a Russian opponent at the world championships in Milan.

One former top Russian fencer expressed his sympathy for Ms. Kharlan on Thursday. Konstantin Lokhanov, who participated for Russia in the 2021 Tokyo Olympics and now lives in San Diego, said in an interview that he thought the disqualification of Ms. Kharlan might have been a trap set by her Russian opponent. Unless overturned, the disqualification in the individual saber competition also could prevent Ms. Kharlan from competing in the team fencing competition at the world championships.

On the one hand, the International Fencing Federation had little choice but to adhere to its rules about shaking hands, said Mr. Lokhanov, who is the former husband of a Russian Olympic fencing champion and the former son-in-law of the president of the Russian Olympic Committee. On the other hand, Mr. Lokhanov said, the tapping of blades was the accepted acknowledgment of an opponent during the pandemic and is still considered suitable by many fencers.

“I support Olga,” he said. “In my opinion she made the right decision. I understand why she made it. But I don’t see any reason why this Russian woman had to make that drama. She could have just touched blades; the bout was over.”

Marc Santora contributed reporting.