Two Hong Kong journalists who led a pro-democracy newspaper were sentenced to jail Thursday after they were convicted of sedition last month in a verdict seen as a further blow to press freedom in the Chinese territory.

Chung Pui-kuen, the former editor-in-chief of the now-defunct Stand News, was sentenced to 21 months, while Patrick Lam, the newspaper’s former acting editor-in-chief, received 14 months as a starting point but after reductions was immediately released because of a serious…