Vietnamese border officials are refusing to stamp new Chinese passports featuring the nine-dash line that represents China's claim on most of the South China Sea.

According to a report by Vietnamese media group Tuoi Tre News on Saturday, holders of these passports are, instead, issued with a separate on-arrival visa. This is to avoid inadvertently recognising China's claim.

Last week, the Arbitral Tribunal at The Hague ruled in a case lodged by the Philippines that the nine-dash line was illegal and breached Manila's territorial rights. China refuses to recognise the ruling.

Vietnam, with maritime claims that overlap China's, has said that it welcomes the verdict but has otherwise been restrained in its reaction.

The vice-chairman of Quang Ninh province's People's Council, Mr Nguyen Xuan Ky, was quoted by Tuoi Tre as saying: "By issuing separate visas, Vietnamese authorities can avoid directly stamping the passports, thus demonstrating Vietnam's stance of not recognising the nine-dash line in any form."

Any such passport stamped by mistake will be stamped "voided" upon the traveller's next entry to Vietnam.

In southern Vietnam's Phu Quoc airport, where foreign tourists do not need a visa for entry, Chinese with the nine-dash-line passport have to fill out a separate entry declaration, media reports say.

Customs officers at Da Nang airport have also confiscated from Chinese passengers many maps featuring the nine-dash line.

Meanwhile, a provincial Vietnamese television station has stopped airing Shanghai Bund, a Chinese remake of a popular Hong Kong series, after its lead actor Huang Xiaoming voiced support for Beijing's claims over the South China Sea, according to online portal VN Express International.

In Hanoi, about 20 people were detained yesterday while protesting against China's rejection of the international tribunal's decision.