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.