A lower-tier appointee, Caspar Tsui Ying-wai, who will become political assistant to the secretary for home affairs, also applied to renounce his Canadian citizenship on Monday.

All three undersecretaries who announced their decisions yesterday cited public opinion as an overriding factor during their deliberations, while also stressing they were personal decisions, taken without any pressure from the government.

They said there was no requirement for them to renounce foreign citizenship since the Basic Law stated that only principal officials needed take such action.

The capitulation of the five undersecretaries was described by an analyst as an indication of the government's naivety and stubbornness in failing to recognise public opinion.

Yesterday, Julia Leung Fung-yee, future undersecretary for financial services and the treasury, said she had applied to renounce her British right of abode. She said she always knew it would be a decision she would have to make 'sooner or later'.

'I have never thought the intensity [of public opinion] would be so great on this issue. In order to prevent public doubts, perhaps this is the appropriate way,' she said.

Gabriel Leung, future undersecretary for food and health, said he had applied to renounce his Canadian citizenship, while Kitty Poon Kit, future undersecretary for the environment, had initiated the renunciation process with the US consulate.

Jeremy Young Chit-on, future assistant to the secretary for education, has yet to announce whether he will relinquish his British citizenship

Chinese University political analyst Ivan Choy Chi-keung said Mr So's move made it impossible for the others to hold onto their foreign citizenship. 'Why did the government not resolve this saga all in one go, but instead let the negative news drag on for a week?' he said.

A government source denied the announcements yesterday were co-ordinated. Executive councillor Henry Fan Hung-ling said it was time to look ahead and focus on training political talent in the run-up to universal suffrage. 'I'm very concerned it will further deter talent from going into politics,' he said.

Renunciations of US citizenship are irrevocable. Britons who renounce citizenship have one chance to resume it, while former Canadians can resume citizenship after living in the country for a year.