TAIPEI, Taiwan — As Taiwan prepares to hold local elections on Saturday, concerns are growing that Beijing’s long effort to sway the island’s politics has been armed with a new weapon: a Russia-style influence campaign.

The island’s elections for city mayors and county and village leaders will in part serve as a report card on President Tsai Ing-wen, whose administration has come under immense pressure from Beijing. But Taiwan officials are sounding alarms at what they say is a campaign by Beijing to spread disinformation that serves its agenda by exploiting the island’s freewheeling public discourse.

“There are those people who mistakenly think that if you simply shout falsehoods loudly, they’ll become real,” Ms. Tsai wrote on Facebook last week. “We must not let them succeed.”

Taiwan officials say the population of 23 million is regularly fed misleading information in the news media and on social networks that range from unverified footage of large-scale Chinese military drills to false reports of stranded travelers being abandoned by the island’s government.