HUNDREDS of children have joined students demanding greater ­democracy for Hong Kong, capping a week-long campaign during which a large cut-out depicting the territory's leader as the devil was paraded through the city amid calls for him to resign.

Secondary school pupils launched a one-day class boycott, supporting the university and college students who began their own class boycott on Monday with a rally that drew about 13,000 people.

"My parents encourage me to have critical thinking and they are most concerned about my safety," said 12-year-old Eren Chak, who wore the trademark white T-shirt and yellow ribbon of the protest movement.

About 200 students camped outside the home of chief executive Leung Chun-ying on Thursday night after he ignored a 48-hour ultimatum to meet them to discuss the former British colony's democratic future as tensions escalate.

"The secondary-school class boycott indicates the red light warning is up for Hong Kong politics," said Joshua Wong, a 17-year-old who heads Scholarism, the group leading the pupils' protest.

Hong Kong returned from British to Chinese rule in 1997 with a high degree of autonomy and freedoms not enjoyed in mainland China under a formula known as "one country, two systems", which espoused universal suffrage as an eventual goal.

But Beijing last month rejected demands for people to freely choose the city's next leader in 2017, prompting threats from pro-democracy activists to shut down Hong Kong's Central financial district.