Hong Kong, China | Gruelling foot drills and camouflage uniforms are part of life for some Hong Kongers as military-style youth groups become increasingly popular, despite the fact there is no army to join.

Some follow the traditions of former British colonial forces, while others are newly invented military-flavoured boot camps designed to keep young people in shape.

But as the semi-autonomous city prepares to mark 20 years since it was handed back by Britain to China in 1997, there are concerns that politics is taking over with the formation of secretive new groups. 

Speculation is rife about the Hong Kong Army Cadets Association (HKACA), whose members wear green uniforms reminiscent of China's People's Liberation Army (PLA).

Its website describes it as a uniform group that provides training in discipline and Chinese-style foot drills, to "cultivate strong willpower... unity and vigour".

It was launched in 2015 -- a year after huge student-led pro-democracy rallies in Hong Kong brought parts of the city to a standstill in an unprecedented challenge to Beijing.

Some observers say the cadets could be a way to get a pro-China message across at a time when younger generations are pushing back, with some campaigning for a split from the mainland.

Political analyst Ma Ngok said the aim was likely "patriotic education".

"Both local and central authorities would have thought it necessary and urgent to start trying to win young hearts and minds," he said.

An official attempt to implement a patriotic curriculum in schools failed in 2012 after massive demonstrations by students, parents and teachers concerned it would amount to brainwashing.

The new cadet group's commander-in-chief is the wife of current Beijing-friendly city leader Leung Chun-ying and some of its honorary patrons include members of the PLA and China's liaison office in Hong Kong.

The PLA has a garrison in central Hong Kong and is responsible for defending the city, but only recruits mainland Chinese citizens. Hong Kong does not have its own separate army.

After the handover some feared the PLA would be heavy-handed, given the army's crackdown on student protesters in Beijing's Tiananmen Square in 1989. 

Instead they have maintained a very low profile and are barred from interfering in local affairs.

But some lawmakers have questioned whether the PLA is providing training or financial support for the cadets.

The youth group's chairman, Bunny Chan, has denied such links. The HKACA turned down multiple interview requests from AFP and when one youth member was approached he said he could not comment.

- 'No ideology' - Last year, in response to the foundation of the cadets, anti-China party Civic Passion launched its own military-flavour youth group.

The dedicated "Passion Teens Squad" has 1,900 Facebook followers and says its aim is physical training and learning Hong Kong's "real history and culture". 

The group's trainer, who identified himself only as Wan, told AFP that activities included hiking, orientation and survival skills.

"We are resisting other youth groups that have links with China," he said.

But members of many more established youth groups say they simply enjoy getting out of the urban sprawl to learn new skills.

At a Saturday session with the Hong Kong Adventure Corps, young recruits marched, climbed walls and spoke into walkie-talkies at their training ground in rural Sai Kung.

The group has around 4,200 youth members and was set up by former staff of the Royal Hong Kong Regiment, also known as The Volunteers, a local branch of the British Army disbanded in 1995. 

Tang Chi-shing, 12, admitted he didn't like it when he joined 18 months ago, but grew to enjoy the challenging training.

"This organisation is one of the toughest in Hong Kong," he told AFP, saying he no longer feared his school teachers as a result. 

Members wear green camouflage and berets and learn everything from map-reading to abseiling. 

"I just wanted to play the games and go rock climbing," recent recruit Hosanna Tse, 14, told AFP, saying she enjoyed wearing the uniform.

Director Matthew Wong served in The Volunteers for 14 years and said that even though the Adventure Corps inherited their drills from the British Army, there was no political aim.

"Our objective is not to train soldiers, but to develop their personal qualities," he said.

Military historian Kwong Chi-man said Hong Kong parents considered the numerous uniform groups -- which also include non-military-style organisations such as the Girl Guides -- as a way to help children become more self-reliant and confident.

Kwong, assistant professor at Hong Kong Baptist University, said any political slant would put them off. 

"If they knew their kids were entering those organisations to become ideological, many of those parents, I would say, would withhold."