The accusation emerged at a Senate hearing where a senior lawmaker claimed Beijing's embassy in Manila was "paying Filipinos to work in troll farms" to undermine President Ferdinand Marcos's government.

The May 12 nationwide poll will decide hundreds of seats in the House of Representatives and Senate as well as thousands of hotly contested local positions.

Senator Francis Tolentino, who is running for re-election on the Marcos slate, said the government's policy in the disputed South China Sea was among the troll farms' frequent targets.

The Philippines has been engaged in months of confrontations with Beijing over the crucial waterway and has steadily deepened defence cooperation with the United States under Marcos.

NSC Assistant Director General Jonathan Malaya told the Senate hearing on Thursday his agency believed China was likely behind online attacks aimed at influencing the polls.

"There are indications... that information operations are being conducted that are Chinese state-sponsored in the Philippines that are actually interfering in the forthcoming elections," Malaya said.

He said the NSC had identified a list of local proxies known to be amplifying Beijing's messaging.

Tolentino said local companies were being paid to create hundreds of fake social media accounts with the intention of swaying the outcome of the election.

"It's clear that the Chinese government, through the Chinese Embassy, is paying Filipinos to work in troll farms to criticise and destroy our administration, our Congress and our government," Tolentino said.

Calls to the Chinese Embassy were not returned immediately.

Asked to comment on the allegations, Philippine Commission on Elections (Comelec) chairman George Garcia called them "dangerous and worrisome".

"We were likewise briefed about attacks directed against Comelec using bots and troll farms" aimed at undermining faith in the coming election, he told journalists in a messaging chat group.

Marcos' popularity has plunged precipitously in the past three months, with a recent poll showing his approval rating effectively halved to just 25 percent since a survey in late 2024.

The drop follows the arrest and transfer of former president Rodrigo Duterte to the International Criminal Court in The Hague to face charges tied to his deadly drug war, and the impeachment of his daughter, Philippine Vice President Sara Duterte.

There has been a major spike in misinformation tied to the case since the elder Duterte's arrest, some of which has been debunked by AFP fact-checkers.

A researcher at Washington's Digital Forensic Research Lab who spoke to AFP's fact-check team last year said he had observed pro-China content circulating in Philippine-based groups, many of which shared Beijing's version of the South China Sea dispute.