"Any proposals to repeal any of the human rights ordinances that currently apply in Hong Kong would be a retrograde step," Mr Rifkind said after a meeting with Singapore's Foreign Minister, Shanmugam Jayakumar.
"Concern has been expressed right across the international community, including the United States, Europe and elsewhere, and we hope the Chinese side will give very serious consideration to these concerns."
Singapore is hosting two days of talks between the foreign ministers of the European Union and the Association of South East Asian Nations (Asean). On Saturday, they will be joined by delegations from South Korea, Japan and China for the so called Asia Europe Meeting (Asem).
The official agenda ranges from the promotion of economic and business links to educational exchanges and the battle against the drugs trade.
But the gathering is being overshadowed by worries about human rights in Burma, East Timor and potentially, in Hong Kong after it reverts to Chinese rule on 1 July.
On Friday Mr Rifkind will meet the Chinese Foreign Minister, Qian Qichen, in what will almost certainly be the last meeting of British and Chinese foreign ministers before 30 June.
In January, relations between Britain and China hit a new low after Peking announced it will amend Hong Kong's Bill of Rights, passed under Governor Chris Patten, restoring colonial-era laws that limit freedom of assembly and association.
The announcement infuriated Mr Patten and provoked a formal British protest. China was sufficiently taken aback by the furore, and by the negative effect that this had on the standing in the colony of its designated head for Hong Kong, Tung Chee-hwa, to announce it would not be necessary to reintroduce the old, repressive colonial laws after all. Instead, it said new, undefined ways would be found to guarantee Hong Kong's "stability".
Mr Rifkind will try to bring about a retraction by Peking of it most hard line statements. A senior aide said: "We don't regard these utterances as immutable and there is still something to play for."
Mr Rifkind will use the opportunity to strengthen the unofficial international coalition pressing Peking to respect human rights and independent institutions in Hong Kong.
"There is an international dimension to this. The world is watching Hong Kong," said the British official. "We've had successes in making sure the US and our main European partners, plus Japan, the Australians and New Zealanders have been speaking out."
The potential gap in the jigsaw lies among the Asean countries. They have been much more reluctant to speak out on human rights. Indonesia has threatened to walk out of this week's meetings if the European side so much as mentions East Timor, the Portuguese colony brutally annexed by Jakarta 20 years ago. The other point of friction is Burma's military government, which the EU regards as a pariah, but which is expected to become an Asean member as early as next year.
Mr Rifkind said yesterday that Burma's military government was "a rather nasty, dictatorial regime", but stopped short of calling for its international isolation.
Singapore (AP) - Police detained and handcuffed an Associated Press reporter during the news conference by Mr Rifkind and his Singaporean counterpart. A police statement said Vijay Joshi "thrust his tape recorder toward the ministers in an overly aggressive manner". He was later released.