Andrew Work, executive director of the Canadian Chamber of Commerce, said the ban would create serious inconvenience for foreigners living and working in Hong Kong.

'This is a real hassle for foreign small- and medium-sized business owners ... it's bound to slow business down and we hope that normal access to the mainland will be restored soon.'

One travel agent who declined to be named said: 'People have been asking to renew their multiple-entry visas but no one can get more than a double-entry visa. We were told this was because of the Olympics and that the ban would be lifted in September after the Games had finished.'

Daryl Bending, of Concord Travel, said even permanent Hong Kong residents who had previously been given three-year multiple-entry visas were affected.

'No one is being given more than a double-entry visa. The reason given was the Olympics but there were suggestions that after the Games things would return to normal,' he said.

Agents said they were told of the move on March 27. Hong Kong-based China-visa agency Forever Bright says on its website the ban will apply until October 17.

The Office of the Foreign Ministry Commissioner in Hong Kong was unavailable for comment.

Mr Work said: 'I found out at a chamber meeting for the chairs of all the chambers in Hong Kong. It's headed by [Chief Secretary] Henry Tang Ying-yen. At the end of the meeting someone mentioned the ban on multiple-entry visas. It took us all by surprise. Even Henry Tang didn't know.'

A senior source from the Hong Kong General Chamber of Commerce said: 'We have got similar complaints and this will hinder business activities.'

A government spokesman said: 'The Hong Kong General Chamber of Commerce recently raised concern about new visa arrangements implemented by mainland authorities and the administration is looking into the matter.'

Travel agents also said the cost of single- and double-entry visas had risen.

The typical cost of a single-entry visa obtained through a travel agent for a British passport holder is now HK$850 for a single-entry visa and HK$1,050 for a double-entry one. At the end of last year, a six-month multiple-entry visa cost HK$1,080.

Australians, Canadians and most Europeans can expect to pay HK$500 for a single-entry visa and HK$600 for a double-entry one. Six-month multiple-entry visas for these nationalities previously cost about HK$450.

The move has surprised Howard Young, the tourism sector legislator.

'The ban will create a lot of inconvenience. I hope it's only temporary,' Mr Young said.

Visas are taking longer to process. Paul Porter, a lawyer and regular mainland visitor, said he had been told a visa now takes four days.