Plans by the Hong Kong post office to cover up British royal insignia on historic mail boxes have sparked a backlash from conservation campaigners and accusations of a push to erase the city's colonial past.

A crown and cypher -- a monogram of the British monarch at the time -- features on 59 post boxes around the city, mostly the insignia of Queen Elizabeth II.

But Hongkong Post described them as "inappropriate" in a city which reverted to Chinese sovereignty in 1997.

It said in a statement it planned to cover up the insignia but would not damage them in the process.

There are more than 1,000 street post boxes around the city and all would display the post office's hummingbird logo to make them "easily identifiable", it said.

The move comes weeks after former Beijing official Chen Zuo'er called for the semi-autonomous city to shake off its colonial past.

Under a "one country, two systems" agreement, Hong Kong has far greater freedoms than the mainland, but there are fears that these are being eroded by increased influence from Beijing.

Hong Kong remains deeply divided over its political future in the wake of mass pro-democracy protests at the end of last year.

British colonial flags have been waved by some anti-government protesters.

Local activist David Webb said the move by Hongkong Post was "political interference".

"This has not been a problem for the post office since 1997, so why now?" he told AFP.

"It can only be because pressure has been brought to bear on them to remove these colonial symbols."

Hong Kong's Conservancy Alliance has also called for the insignia to be left alone and launched a Facebook page asking contributors to post pictures of the mail boxes.

Source: AFP