Britons and other foreign nationals living on the mainland are legally required to keep their passports with them. But under new British rules, citizens needing to renew their travel documents must send them to the regional passport processing centre in Hong Kong.
If they comply with those rules, Britons risk being fined or detained by mainland authorities, diplomats said, although the potential penalties are vague.
Jo McPhail, head of the overseas passport management unit at Britain's Foreign Office, said China and South Korea were among eight or nine countries where it was a legal requirement for people to have their passports available for inspection.
She said these restrictions were recognised by passport processing centres, which would accept a complete photocopy of the passport being renewed rather than the original document. McPhail said that although a photocopied passport renewal was allowed, officials wanted to keep the number being processed to a minimum.
Britons sending a photocopied passport may also have to wait up to six weeks for a new passport to be couriered from Britain rather than the maximum processing time of four weeks when the original document is submitted for renewal.
The Foreign Office changed procedures earlier this year so that Britons in Asia must apply to the Hong Kong regional passport production centre for new passports.
British citizens making passport renewal applications in jurisdictions including Hong Kong have to surrender their passports, which are automatically retained, marooning them until the new passport is delivered. One option for frequent travellers, including those travelling between Hong Kong and the mainland on a regular basis, is to apply for a second passport, although applications are only considered for business reasons and on a case-by-case basis, British officials say.
Paula Corrans, manager of the Asia passport production centre at the British consulate in Hong Kong, said: 'For all applications, other than for second passports, the old passport is automatically cancelled by the system part-way through the processing. We cannot guarantee when this will be, as processing times differ depending on the complexity of the application and during peak and quiet periods.'
Changes in the way passport applications are made and processed were introduced in August for cost and security reasons, albeit with little publicity. They also prevent Britons from travelling, except for urgent trips when an emergency travel document can be issued.
Other countries - including France, the United States and Canada - continue to allow their nationals to travel on an existing passport after an application for a replacement has been made.
A spokesman for the US consulate said that, except for applications for emergency passports, 'All applications are processed locally, the data is transferred electronically to the US and the passport hard book is manufactured there.'
He said new passports, which are issued in five to 10 working days, are also issued locally.
'The old passport must be presented for cancellation before the new passport can be given to the applicant. At this point, the cancelled passport booklet no longer serves as a valid travel document but does retain value as proof of identity and US citizenship,' he said.
Passport Canada spokeswoman Beatrice Fenelon said that while applications are made locally, passports are issued in Canada. But citizens applying outside Canada can retain their passport until the new one is issued or collected from the local consulate or embassy, whereupon the old document is cancelled.
A spokeswoman at the French consulate said new passport applications are made locally and citizens can continue to use their existing passport until they collect their new one.