A top editor of a weekly newspaper who recently called for the reform of China’s onerous household registration system, which restricts where people can live, has been forced out of his job in a fresh warning that journalists who boldly challenge government policy face retribution. The dismissed journalist, Zhang Hong, had been deputy editor in chief of the Web site of the Economic Observer, which is based in Beijing. Two Chinese media sources reached by telephone said he was fired because of his efforts to unite a group of journalists to criticize the registration system, which ties Chinese to their parents’ hometown if they want government services. In a letter leaked to selected Chinese and foreign journalists on Tuesday, Mr. Zhang wrote that after the editorial was published, “I was punished accordingly; other colleagues and media partners also felt repercussions.”On March 1, just days before China’s annual legislative sessions, Mr. Zhang’s newspaper and a dozen other Chinese publications published his editorial, asserting that the registration system unfairly restricts the right of Chinese citizens to seek a better life outside their hometowns. The editorial vanished from the Internet within hours, the victim of China’s censors, but not before it was picked up by foreign news outlets. The publication of the editorial by 13 big-city newspapers, financial publications and regional dailies effectively served as a test of where the government draws the line. It was especially provocative because it was an organized effort, not an individual’s complaint. Propaganda authorities reacted by launching an investigation and issuing an official warning to the Economic Observer.