Simon Cheng was reported missing on 8 August after crossing the border for a business trip.Read more
Hong Kong anti-government protests
Canada has blocked local staff at its Hong Kong consulate from travelling on official business.
Global Affairs said in a statement to the BBC that local staff "will not undertake official business travel outside of Hong Kong".
However, Canadian diplomats attached to the consulate will still be able to travel.
Canadian officials have not said whether or not the block relates to the detention of a worker at the UK's Hong Kong consulate at the Chinese border during a business trip.
The decision comes at a time of heightened tensions between China and Canada, inflamed by the arrest of Meng Wanzhou, an executive with Chinese telecoms firm Huawei.
Cathay Pacific employees say they fear losing their jobs if they express support for pro-democracy protesters in Hong Kong.
Employees of the airline told the BBC that staff feared working routes to mainland China.
Some are considering bringing decoy mobiles with them in case their phones are checked on arrival in the mainland.
It comes weeks after China demanded the airline suspend staff involved in the protest movement.
Protesters have been taking to the streets of Hong Kong for the past 11 weeks. The demonstrations were originally against an extradition bill but have now evolved into a wider pro-democracy movement.
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A sit-in at Yuen Long train station ended with a stand-off between police and some protesters.