HONG KONG • Veteran Cantopop star Alan Tam, 71, has denied an allegation by a Weibo user that he had an affair with the man's 23-year-old girlfriend.

The accusation first surfaced on Tuesday on the Chinese social media platform from an account called Sad Beef Noodles.

The man claimed to have discovered the affair when he accessed his girlfriend's phone to buy her some items from her shopping cart. He then found out that his girlfriend, a fan of Tam's, had a secret folder of photos and had lied about going to Shanghai to shop with a friend.

He tagged Tam, also known as Ah Lun or Principal Tam, in the post, which has since been deleted.

Tam's management agency, Impact Entertainment, issued a statement on Weibo on Wednesday night refuting the allegations.

"As is well known, Mr Tam has loved his work passionately for the past decades, supported the younger generations, contributed to his country and to society, and respected his fans," said the statement, which Tam also shared on Weibo. "As someone who sits on the Hong Kong Election Committee, he will not ignore actions that damage his reputation and will take appropriate legal action."

Sad Beef Noodles fired back another salvo, this time uploading two photos.

One showed the back view of a man sitting on the edge of a bed, either taking off or putting on his trousers. The other was a screenshot of voice messages allegedly from Tam to his girlfriend.

"If you dare to make another statement, I will continue to attack," he wrote, adding that he would pursue the matter to the end.

The photos were later deleted, but netizens noticed that the man in the photo had similar black sneakers to those worn by Tam in the past and the hotel appeared to be the same one he had been quarantined in.

Tam, a megastar in the region in the 1980s with 115 solo albums under his belt, has been active in China in recent years.

He is still legally married to his wife, Ms Sally Yeung, even though they have led separate lives since his affair with his current partner, Ms Wendy Chu, whom he married in 1991 and has a son with.