(Reuters) - Hundreds of school children joined university students demanding greater democracy on Friday, capping a week-long campaign that has seen a large cut-out depicting Hong Kong's leader as the devil paraded through the city and calls for him to resign.

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.

Secondary school pupils led by the group Scholarism began a one-day boycott of classes on Friday, supporting a week-long strike by university and college students that started on Monday with a rally that drew about 13,000.

"CY chose to use the police as a barricade against the 4,000 students and citizens who marched to his home yesterday, refusing to face the call for a face-to-face communication," said Lester Shum of the Hong Kong Federation of Students, referring to Leung.

"I believe the Hong Kong people will see and remember this cowardly and ugly side of him."

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".

But Beijing last month rejected demands for people to freely choose the city's next leader, prompting threats from pro-democracy activists to shut down the Central financial district. It wants to limit 2017 elections to a handful of candidates loyal to Beijing.

About 20 students tried to break through the security cordon to Leung's front door but were stopped by police who took their identity card numbers.

The students' ability to mobilise thousands to fight for democracy has made their support an increasingly important driver of the city's burgeoning civil disobedience movement.

The protests have taken place in a grassy, harbour-front park flanking government headquarters and near the heart of Central. The demonstrators are demanding full democracy in a series of escalating acts that will culminate in an "Occupy Central" blockade on Oct. 1.

(Additional reporting by Yimou Lee; Writing by Anne Marie Roantree; Editing by Nick Macfie)