TAIPEI/BEIJING (Reuters) - China has sailed its new aircraft carrier into the Taiwan Strait, Taiwan’s defence ministry said on Thursday, as a presidential election campaigning was in full swing on the island amid heighten tension with Beijing.

A military honour guard holds a Taiwanese national flag as he attending flag-raising ceremony at Chiang Kai-shek Memorial Hall, in Taipei, Taiwan March 16, 2018. REUTERS/Tyrone Siu/Files

Democratic Taiwan is claimed by China as a wayward province and is the Communist Party’s most sensitive and important territorial issue. China has threatened to attack if Taiwan moves toward formal independence.

Taiwan holds a presidential vote on Jan. 11 with President Tsai Ing-wen hoping to win re-election. She has repeatedly mentioned what she sees as the threat of China as a warning to voters.

Tsai’s ruling Democratic Progressive Party is pro-independence, although she has said she wants to maintain the status quo with China but will defend Taiwan’s security and democracy.

The Chinese carrier Shandong sailed north through the Strait, the Taiwan ministry said in a short statement, adding that the carrier group was accompanied by frigates. The ministry did not say exactly when the ships made their voyage.

“It’s the responsibility and duty for the two sides across the strait to maintain peace and stability and strive for the well-being of the people,” Taiwan’s presidential office said in a statement.

“Beijing should cherish peace and stability across the strait and in the region, which are not easy to come by.”

China’s defence ministry did not immediately respond to a request for comment.

A senior Taiwan official familiar with security planning said the Chinese navy patrol was the latest bid by Beijing to meddle in Taiwan’s election.

“By flexing military muscles, China is trying to intimidate non-aligned voters,” the official, who declined to be identified, told Reuters.

“Beijing understands that this could be a double-edged sword, but what worries China more is the possibility of a fiasco for pro-China forces in the election.”

China would prefer to the see the candidate of the main opposition Kuomintang party, which backs stronger ties, win the election.

The Chinese ministry’s spokesman, Wu Qian, speaking earlier on Thursday at a monthly news briefing, said everything was going “smoothly” with the new carrier, though did not comment on its deployments.

“It will continue to conduct trials and training, and form a combat capability through training. We will make an overall consideration about its deployment according to the situation and task needs,” Wu said.

He did not mention its sailing through the Taiwan Strait.

The carrier, China’s second largest, entered service at a base in the South China Sea last week in a big step in the country’s ambitious military modernization.

Last month, the ship, still unnamed at the time, sailed through the Taiwan Strait on its way to what China called routine exercises in the South China Sea, with Taiwan scrambling ships and aircraft to monitor the group.

President Xi Jinping said in January that China reserves the right to use force to bring Taiwan under its control but will strive to achieve peaceful “reunification”.