A police helicopter patrols behind Hong Kong flag as Chinese President Xi Jinping leaves the hotel, ahead of 20th anniversary of the handover from Britain to China, in Hong Kong, China June 29, 2017. REUTERS/Tyrone Siu

LONDON (Reuters) - Britain’s foreign ministry said on Monday that it was concerned by the decision by Hong Kong to ban a group promoting independence from China, the first outlawing of a political organisation since Britain handed its former colony back.

The city’s secretary for security announced the ban on the Hong Kong National Party using a previously little noticed colonial-era law that requires all social groups and organisations to register with the police.

“We are concerned by the decision,” Britain’s foreign ministry said in a statement. “The UK does not support Hong Kong independence, but Hong Kong’s high degree of autonomy and its rights and freedoms are central to its way of life, and it is important they are fully respected.”

Britain handed Hong Kong back to China in 1997 under an agreement which said it could keep its wide-ranging freedoms and autonomy.