From the BA website...

*Countries where BA Holidays are available are:

• In Europe: UK, Germany, France, Italy, Ireland, Netherlands, Switzerland, Spain, Denmark, Sweden, Norway, Austria, Belgium, Bulgaria, Cyprus, Czech Republic Finland, Greece, Croatia, Hungary, Poland, Portugal, Romania, Russia.
• In the Americas: USA, Canada, Argentina, Barbados, Bermuda, Bahamas, Chile, Grenada, Jamaica, Cayman Islands, Mexico, St Lucia, St Kitts and Nevis**, Turks and Caicos, Trinidad and Tobago.
• In the rest of the world: South Africa, Hong Kong, Australia, Singapore, United Arab Emirates, India, New Zealand**, Egypt, Israel, Turkey.

(**British Airways doesn't offer packages in these countries.)

So Hong Kong is there but not the rest of China. Nor is Thailand, Korea, etc. But they do have Singapore!