Who is Jia Jia, Chinese columnist missing over letter asking President Xi to resign?

The controversial letter called for Xi's resignation, saying he did not have the leadership skills to take China forward

Jia Jia, a prominent Chinese columnist, has gone missing for several days, his family and lawyer have said.

Hong Kong media said his disappearance is connected to an open letter in a Chinese state-linked publication that called for the resignation of President Xi Jinping.

Jia's wife said he last contacted her from the airport on Tuesday night to say he had gone through security and customs clearance for boarding a flight to Hong Kong.

The anonymous letter titled "loyal Communist Party members, which severely criticised President published earlier this month on Xi on Wujie News. It has been reported that Jia had warned a journalist friend over the publication of the letter, which was taken down swiftly following the backlash.

Jia, who writes a column for Tencent and teaches at the Sun Yat-sen University in Guangzhou, reportedly denied he had penned the letter.

Jia's wife says his phone went dead 15 minutes after he spoke from the airport and that he could not be reached since then. The 35-year-old social commentator did not reach Hong Kong as scheduled.

"We don't have any clue who took him away and why... there is [a] great possibility that he was taken away from the airport," Jia Jia's lawyer His lawyer Yan Xin told BBC.

"His wife has not received any official document on Jia Jia's whereabouts and status.

The controversial letter was addressed to Xi and called for his resignation, saying he did not have the leadership skills to take China forward.

The letter also criticised the "excessive power' Xi accumulated and the "personality cult" that thrived around him.

"Your condoning of a personality cult, not allowing 'rash opinions of central leadership', creating a 'one voice party' method - those of us who have gone through the Cultural Revolution can't help but feel secretly worried - our party, country and citizens cannot go through yet another 10-year catastrophe!," the letter says.

The full text of the letter, published by the China Digital Times, can be read here.