At least one business traveller has been stranded in Hong Kong by the restrictions, which were disclosed on Monday to travel agency couriers and came into effect on Tuesday.

The rules have been issued by the Commissioner's Office of the Foreign Ministry in Hong Kong.

Among the 33 countries whose nationals, travel agents say, can no longer get visas in Hong Kong are Malaysia, the Philippines, Indonesia, India, Sri Lanka, Nepal, Saudi Arabia, South Africa, Nigeria and Turkey. The ban does not apply to people from these countries living in Hong Kong.

The changes come days after travel agents said they had been told on March 27 that no new multiple-entry visas would be issued until October. In addition, immigration offices at the border stopped issuing short-stay visas to Shenzhen on April 1, when the commissioner's office took over the issuing of all visas.

The office said yesterday multiple-entry visas could still be issued.

The moves have provoked acute concern from chambers of commerce, who fear the interests of Hong Kong companies will be damaged.

Daryl Bending, senior travel consultant with Concorde Travel, said: 'We were told late on Monday with pretty much immediate effect that anyone wishing to travel to any mainland destination was required to have a copy of the airline ticket and the hotel voucher before they apply for a visa.

'We were also told about a new visa for entering Shenzhen, which will effectively replace the on-the-spot Shenzhen visa that used to be issued at the border.

'Previously, if you went up to the border you could get a visa there, which was for approximately five days. We were told on Tuesday that the hotel voucher and proof-of-travel requirement would also apply to Shenzhen whether the passenger goes by boat, train or car.'

Mr Bending said: 'I think the restrictions will deter some foreign tourists from travelling to China at all and ... put an end to much of the casual traffic from Hong Kong to Shenzhen for shopping and recreation.'

The Commissioner's Office yesterday released a statement confirming that a return ticket and a hotel voucher was required for a tourist visa and an additional 'visa notification form' for a business visa. It said the measure was 'to spare applicants unnecessary trouble'.

It did not respond to queries about a new Shenzhen visa or new requirements for 33 nationalities.

A Hong Kong government spokesman said: 'The government has reflected the views and concerns of the Hong Kong business community to the mainland authorities.'

Rob Schlipper, of Outpac Designs, which makes travel security products with a Shenzhen firm, said the changes were 'a devastating blow'.

Malaysian consul general Cheong Loon Lai said the consulate had received a request for help from a Malaysian businessman who made a day trip to Hong Kong during a business trip to the mainland and was not allowed back over the border.