Thousands attend an annual pro-democracy march in Hong Kong Friday July 01,2016

Tens of thousands of protesters have attended an annual pro-democracy march in Hong Kong.

Protesters held photos of Lam Wing Kee, one of five booksellers who went missing last year after publishing books critical of China's leaders.

Lam Wing Kee returned to Hong Kong in June 2016,saying he had been detained in the mainland for eight months.

He was due to lead Friday July 01,2016 's march but dropped out, reportedly over fears for his personal safety.

The case of the booksellers raised international concerns that Hong Kong's judicial independence and freedom of speech were being eroded.

The 1 July march marks 19 years since the territory's handover from Britain to China.

Organisers said 110,000 people attended the march, while police said there were 19,300 demonstrators at the peak of the protest.

Marchers also called for the resignation of Chief Executive CY Leung, who has faced criticism for what protesters say was a failure to protect the booksellers.