Cosmetics giant Lancome closed some outlets in Hong Kong Wednesday as protesters gathered at a major mall after the company cancelled a concert featuring a local singer who is critical of China.

Many Hong Kong residents believe the promotional gig by pro-democracy activist Denise Ho was cancelled after China's state-run media criticised the French company for allowing her to perform.

Ho was a leading activist during mass rallies in 2014 calling on Beijing to allow fully free elections.

The row comes as fears grow in the semi-autonomous city that Beijing is tightening its grip.

Dozens of protesters gathered at the Times Square shopping mall in Causeway Bay district Wednesday afternoon shouting: "Boycott Lancome!" and "Shame on self-censorship!"

Carrying cardboard cut-outs of Ho, they entered the mall and stuck posters all over the Lancome counter, which had shut for the day ahead of the demonstrations.

In the same building, a Lancome beauty centre and the offices of parent company L'Oreal were also closed. Local media said the company had issued an internal memo Tuesday asking staff to take the day off.

Organisers warned of more action unless the company responds to growing public anger.

"The key point of this protest is to show the world that we should unite together and, through boycotting (their products), show Lancome and L'Oreal that you cannot just focus on the China market," said Avery Ng, chairman of the League of Social Democrats, one of a dozen groups planning to join the protest.

Shoppers in the busy mall stopped to watch the demonstration and take photos.

"I'm worried that commercial organisations in Hong Kong will increasingly come under Chinese influence," said passer-by Natalie Chan, a researcher in her 40s, adding that she had stopped buying L'Oreal products.

Calls to L'Oreal's Hong Kong office went unanswered and the latest statement from Lancome is dated Sunday, the day of the concert's cancellation.

- 'Stop kowtowing' -

A petition on the website change.org asking people to boycott Lancome products has gathered more than 4,000 signatures.

"The civilised world needs to stop kowtowing to China. Make an example of Lancome for disrespecting the people of Hong Kong and freedom," Lawrence Lau from Hong Kong commented on the site.

Politicians have also voiced anger.

District councillor Christine Fong flushed her Lancome products down the toilet in a video posted on Facebook and watched more than 128,000 times.

"I'm going to squeeze out all of this brand's product and I will never use them again. Lancome go to hell!" she said, squeezing a tube of cream down the toilet.

The row began Saturday when China's Global Times accused Lancome of cooperating with a "Hong Kong poison" and a "Tibet poison" -- a reference to Denise Ho's praise for the Dalai Lama.

The concert was also slammed on mainland social media, with critics saying Lancome was using money from Chinese customers to support independence for Hong Kong and Tibet.

Lancome announced the cancellation of the concert Sunday, citing "possible safety reasons".

Ho, who was not at Wednesday's protest, hit back.

"This incident is serious because Hongkongers have been under political pressure for quite some time," she told AFP, describing what she termed bullying tactics by China as "a message of fear to other brands".

Hong Kong was returned to China in 1997 under a "One country, two systems" agreement and enjoys far greater liberties than in mainland China, but there are fears these are being eroded.