Russian President Vladimir Putin speaks during a campaign concert as supporters, celebrities and dignitaries look on at Luzhniki Stadium on March 3, 2018 in Moscow, Russia.

More voters could turn out for Russia's presidential election on Sunday after the U.K. blamed Moscow for a nerve agent attack in England and announced a series of penalties against Russia, an analyst said Wednesday.

Otilia Dhand, senior vice president at Teneo intelligence, said the sanctions could prompt more Russians to take part in the vote, something the Kremlin is anxious about.

"President Vladimir Putin is well-positioned to win the March 18 presidential election without a need for a run-off," Dhand wrote in a note.

"However, the Kremlin is also keen to drum up high turnout to equip Putin with high legitimacy and will use (Theresa) May's announcement to invoke siege mentality and bring more voters to the ballot box on Sunday."

On Wednesday, U.K. Prime Minister May said she had expelled 23 Russian diplomats — identified as "undeclared intelligence officers" — and was taking measures to "dismantle (Russia's) espionage network." It is the single biggest expulsion in over 30 years.

The penalties come after Sergei Skripal, a former Russian spy-turned-double agent for the U.K., and his daughter Yulia were subject to a nerve agent attack in Salisbury, England, on March 4. They remain in a critical condition in hospital.

Dhand has previously noted that polls had so far indicated that voter participation was likely to "fall well below the Kremlin's unofficial target of 70 percent."

Putin is widely expected to win the election with a strong lead ahead of the other seven candidates running, but the authorities are keen to get people out to vote to improve the semblance of legitimacy.

"The regime in Russia is authoritarian but it requires a certain acquiescence from the populace," Daragh McDowell, principal Russia Analyst at Verisk Maplecroft, told CNBC on Thursday.

"Voter turnout can be the key way to show that people are enthusiastic about, and willing to engage with, the state," he said. "If turnout numbers are continuously falling, then you have legitimacy issues."

McDowell didn't believe the spy attack in the U.K. would factor in the lead-up to the vote on Sunday, saying Putin was unlikely to mention it.

The Russian embassy in London issued a statement Wednesday, following May's announcement, saying, "We consider this hostile action as totally unacceptable, unjustified and shortsighted. All the responsibility for the deterioration of the U.K.-Russia relationship lies with the current political leadership of Britain."