A university student in California has filed a class-action lawsuit against video app TikTok, which she accuses of harvesting large amounts of user data and storing it in China.

“TikTok clandestinely has vacuumed up and transferred to servers in China vast quantities of private and personally-identifiable user data,” the court filing said.

Misty Hong, a student in Palo Alto, California, filed the suit against the Chinese-based app in California federal court last week, according to a report in The Daily Beast on Monday.

The video platform, which is hugely popular with teenagers around the world, was launched by Chinese company ByteDance in September 2017.

“TikTok also has surreptitiously taken user content, such as draft videos never intended for publication, without user knowledge or consent,” the lawsuit alleges.

“In short, TikTok's lighthearted fun comes at a heavy cost,” it said.

The suit marks the latest legal battle for the app. In early November, the US government opened a national security investigation into TikTok, according to the New York Times, potentially looking into whether the app was sending data to China.

Hong alleges that the app retrieved her data without permission – including videos that she had created but not shared online – and transferred them to servers run by companies that cooperate with the Chinese government.

She filed the suit on behalf of the approximately 110 million US residents who have downloaded the app. TikTok did not immediately reply to AFP's request for response.

In November, it said it could not comment on a possible US investigation but emphasised that the respect of US users and regulators was its highest priority.

TikTok has distanced itself from Chinese authorities, maintaining that its servers are located outside of the country and that its data is therefore not subject to Chinese law.

In November, the app hit 1.5 billion downloads worldwide, outperforming Instagram.