A photo frame commemorating the 1989 Tiananmen Square massacre has been allowed on Facebook with an apology from the social media giant to its creator.

A layer of text, called a frame, was designed by Hong Kong activist Fung Ka Keung calling on China to redress the massacre, but it was rejected by Facebook on the grounds that it "belittles, threatens or attacks a particular person, legal entity, nationality or group".

Fung is the chief executive of the Hong Kong Professional Teachers' Union, who used Facebook's newly-introduced service to make the frame. He wrote "June 4 28th Anniversary", "Vindicate June 4th" and "End Dictatorial Rule" on his creation.

A new service that Facebook launched in December 2016 allows users to design text and graphics as frames to overlay on their profile pictures. It has been widely used by activists and rights workers to support different causes or in the wake of certain significant incidents.

But the frames must first be submitted to Facebook for approval. Fung submitted his Tiananmen-themed work as per the guidelines but it got rejected as it did not meet official policies.

Reports say that criticism from Hong Kong media outlets, some of whom questioned whether it was an act of censorship, could have compelled the giant to overturn its position.

Facebook is banned in China, but Taiwan and Hong Kong are among its users.

However, with Facebook reversing its decision, around 2,600 users were currently using the frames, Fung said, adding that he thought Facebook had made some "pretty strange decisions".

"I wouldn't be surprised if political motivations were behind the decisions. I doubt they would have been approved if what happened wasn't publicised," Fung added.

"The frame was disapproved incorrectly. We apologise for this mistake and have let the user know we approved his submission," Facebook said in response.

The development comes a week before the 28th anniversary of the bloody crackdown on activists on Tiananmen Square. The 4 June 1989 pro-democracy movement led by students in Beijing was suppressed by the government with an unknown number of unarmed civilians being killed during the crackdown. The incident is a highly sensitive issue in China.

hong kong tiananmen
Pro-democracy supporters carry a wreath to mourn those who died in the Tiananmen Square massacre Bobby Yip/Reuters