HONG KONG -- China has imposed further curbs on business and tourist visitors, just days after it stopped issuing multiple-entry visas, Hong Kong travel agents said Friday.

"You now need a copy of your travel ticket both in and out of the country and a hotel voucher before they accept a visa application. Without that they will reject it," said Daryl Bending, a travel consultant with Concorde Travel.

"I think it will deter a lot of people from travelling to China. They will just think it is too hard."

Another agent said visitors from around 30 countries -- including Thailand, the Philippines and Indonesia -- were no longer allowed to apply for China visas in Hong Kong and would have to apply at their local Chinese embassies.

"It is becoming more and more serious, it is really out of control," said the travel agent, who did not want to be named.

She said that visas were also now coming back later and later, leaving travellers waiting around for hours to see if their application had been accepted.

A statement on the website of the Chinese Foreign Ministry in Hong Kong said that there had been a "recent drastic rise" in the number of applicants.

"To spare applicants of the unnecessary trouble, for non-resident of Hong Kong, please apply for the Chinese visa at the Chinese embassy or consulate-general in his or her home country or resident country," it said.

It did not mention the list of about 30 countries the agent referred to and insisted multiple-entry visas were available, although it added officials would "consider the real need of the applicant" when granting one.

Travel agents in several Asian countries previously said China had stopped issuing multiple-entry visas several weeks ago and they had been told the service would not be resumed until after the Olympics.

That move provoked concern among the business community here, many of whom have operations across the border.

Hong Kong has maintained separate legal and visa systems since it was returned to China by colonial power Britain in 1997.