Hong Kong said Monday it would delay the introduction of mandatory "national education" classes, which have been criticised as a bid to brainwash children with Chinese patriotism.

Education Secretary Michael Suen said he would follow a committee's recommendations to delay their introduction until 2015 instead of this year as previously planned, to give schools more time to prepare.

But he defended the idea and sought to play down concerns that children in the former British colony would be subjected to an hour a week of nationalist propaganda from the communist authorities in mainland China.

The classes will provide a "more systematic, holistic and sustainable learning experience that can cater for their developmental needs and cultivate their moral and national qualities through a value-based curriculum", he said in a statement.

"This subject emphasises the nurturing of positive values and a responsible character.

"It enables students to acquire desirable personal, moral and national qualities, enriching their life and facilitating their identity-building in the domains of family, society, the country and the world."

The Hong Kong Professional Teachers' Union last year called on the government to block the proposal, which it described as "political interference" from the mainland.

Hong Kong returned to China in 1997 as a semi-autonomous territory with its own political and legal system that guarantees civil liberties not seen on the mainland, including freedom of speech and association.

Anti-Beijing protests are a regular fixture in the regional financial centre of seven million people.

Under the proposal students would take 50 hours of lessons a year focusing on "building national harmony, identity and unity among individuals".

There would be no exams, but classes would assess if pupils "feel happy to be Chinese" or "consider the needs of the country when planning their future", according to guidelines posted on the website of the Education Bureau.