The protest comes after Hong Kong rejected journalist Victor Mallet's application to renew his work visa.
Hong Kong lawmakers demonstrated on Wednesday in support of media freedoms following Hong Kong's rejection of a work visa for a senior British journalist, as city leader Carrie Lam was about to give her annual policy address.
Chanting "Protect media freedoms" and holding placards that said "Free Press. No Persecution", more than a dozen pro-democracy lawmakers walked out of the city's legislative council before Lam gave a 45 minute speech laying out policy priorities for the year.
The protest comes after Hong Kong last week rejected an application for Victor Mallet, the Asia editor for the Financial Times newspaper and first vice-president of the city's Foreign Correspondents' Club, to renew his work visa.
Earlier this year, he hosted a lunch speech by Hong Kong independence activist Andy Chan at the Hong Kong FCC, an event that drew strong condemnation from Chinese and Hong Kong officials.
However, the visa denial has kicked off a storm of protest and has drawn criticism from the United States and Britain. The UK's foreign secretary, Jeremy Hunt, on Tuesday suggested the visa rejection was "politically motivated" and he called on authorities to reconsider.
Since taking office last July, Lam has faced several challenges including an economy and financial markets left vulnerable by the US-China trade war, and one of the world's priciest property markets.
Political tensions between democracy and independence activists resisting China's tightening grip on the city, have continued to simmer.
In her speech, Lam gave her strongest warning yet against those seeking to split Hong Kong from China.
"Hong Kong will not tolerate any acts that advocate Hong Kong's independence and threatens the country's sovereignty, security and development interests.
"We will fearlessly take actions against such acts according to the law in order to safeguard the interests of the country and Hong Kong," Lam wrote in a full-text version of the policy address.
China considers Hong Kong to be an inalienable part of the country, and senior Chinese officials including President Xi Jinping have warned any undermining of national sovereignty is a "red line" that cannot be crossed.