China has "very diverse" ways of interfering in Taiwan's elections in January, from military pressure to spreading fake news, including manipulating opinion polls, according to a senior Taiwanese security official.

Ahead of elections, Taiwan routinely flags the risk of interference from Beijing, which claims the democratically governed island as its own, saying China seeks to sway the outcome to candidates who may be more favourable toward the country.

"The way the Chinese Communists interfere in elections is very diversified," Taiwan National Security Bureau Director-General Tsai Ming-yen told lawmakers during a parliamentary committee session.

China can use military pressure, economic coercion or fake news to create a false choice between "war or peace" in the election, seeking to frighten voters, Tsai said.

"We are paying special attention to the Chinese Communists cooperating with opinion poll and public relations companies for the possibility of manipulating opinion polls and issuing them to interfere in the elections," he added, without naming any companies.

China's Taiwan Affairs Office did not answer calls seeking comment. China is in the middle of its weeklong national day holiday.

Taiwan Vice President William Lai of the ruling Democratic Progressive Party, which champions the island's separate identity from China, is the favourite to be the next president, according to opinion polls.

China considers Lai and his party to be separatists and has repeatedly rejected their offers of talks. Lai says that he does not seek to change the status quo across the Taiwan Strait, but that only Taiwan's people can decide their future.

China has increased military activities around Taiwan since the last election in 2020, and regularly sends warships and fighters into the seas and skies near the island.

Tsai said China's most recent drills close to Taiwan, which started last month and have been described by Taiwan's defence minister as "abnormal", were virtually the same as those in previous years in terms of their focus, such as landing exercises.

But more aircraft and ships were involved this time and there were more practice firings by the People's Liberation Army Rocket Force (PLARF), which oversees China's conventional and nuclear missiles, he added.

That might be related to Chinese President Xi Jinping seeking to exert his control over the PLARF, Tsai said, a branch of China's military that has come under focus after its two most senior leaders were suddenly replaced at the end of July with outside commanders.