BERLIN, April 8 (Reuters) - When Simon Harris became Ireland's prime minister-in-waiting in March, he turned to a favoured platform to express himself: TikTok.

In a video with 'THANK YOU' written in yellow lettering, the man who will be Ireland's youngest Taoiseach told his 95,000 followers of his rise from an "opinionated, moody teenager" bristling at lack of educational help for his autistic brother.

Harris, sometimes dubbed the "TikTok Taoiseach", is among a vanguard of European politicians embracing the Chinese-owned social media platform, calculating that the need to reach younger voters outweighs security concerns.

With European elections approaching in June, mainstream politicians are wary of ceding ground to fringe parties who have successfully exploited its short video format.

But TikTok is under increasing scrutiny in the West due to fears that user data from the app owned by Beijing-based company ByteDance could end up in the hands of the Chinese government.

Germany's security agencies, for example, have warned against using the app over concerns it could share data with China's government or be used to influence users.

In the U.S., lawmakers want to force a sale of the platform by its Chinese owner or ban it from app stores. President Joe Biden has raised concerns with Chinese President Xi Jinping.

TikTok says security warnings are unwarranted and it does not collect more information than other apps.

In a bid to assuage concerns, it launched, opens new tab a site to store European users' data in Dublin last year and hired a third-party security firm to monitor data flows.

ByteDance has denied using its product for spying, while the Chinese government has also denied any such intention.

Harris, 37, was an early adopter in March 2021, producing videos that ranged from a 60-second budget summary with musical background to footage of him making a cup of tea when watching football.

Another was French President Emmanuel Macron, who boasts 4 million followers since joining TikTok in 2020.

In Germany, the embrace of TikTok by senior politicians is a newer trend, with Health Minister Karl Lauterbach becoming the country's first minister to open an account in March.

"Revolution at TikTok: it starts today," he said.

"We cannot leave social media to the AfD", he said, of the far-right Alternative for Germany (AfD) party that surged to become Germany's second-most popular.

He was joined on Monday by his boss, German Chancellor Olaf Scholz, who launched his own TikTok account and said on X: "I won't dance. Promise."

The caption for his first TikTok video, set to quirky music, read: "We are just as surprised as you are! (And yes, the Chancellor really is on TikTok now)".

Germany's top ministers have long had an established presence on other social media. For example, Scholz, the finance minister, the economy minister and the foreign minister all have Instagram accounts, as does Lauterbach.

Reaching young voters is particularly pressing as 16-year-olds in Germany can vote in the June European elections.

Photo from Reuters