Fang said he had lost S$100 (HK$567) in the hour after Marina Bay Sands' opened.

A Shenzhen public security official in charge of reviewing applications for overseas travel said there were no restrictions on residents visiting Singapore, although civil servants had to get their supervisors' approval.

The official asked not to be named as he was not authorised to give the information.

He said it was now extremely difficult, if not impossible, for Shenzhen civil servants to make private visits to Macau.

Some government employees in Shenzhen and Guangzhou said their recent applications to visit Macau had been rejected.

A limit of one Macau visit every two months was still in place for Guangdong residents who were not civil servants, Zhang Yao, a Guangzhou-based manager for China Travel Service said. Approval of applications by mainlanders qualified to visit Macau normally took two or three weeks.

He said Guangzhou civil servants in sensitive departments such as the police, judiciary and state-owned banks, were limited to one Macau visit a year. But Zhang said there were no restrictions on Singapore visits by ordinary residents or government employees.

Las Vegas Sands chairman Sheldon Adelson said after opening his Singapore casino that Beijing would not crack down on mainlanders travelling there.

'This country only has a small percentage of visitors that come from China,' he said. 'I don't believe they'll punish Singapore because they've got a casino there.'

But the billionaire was bullish on Macau's casino revenue growth, pointing to Chinese people's penchant for gambling. Asked whether Macau's growth would stop, he said: 'Never.

'In order for Macau to stop growing, the culture of Chinese people will have to change. I never see that happening.'

Macau raked in US$14.9 billion in gambling revenue last year, up 9.6 per cent on 2008.

The numner of mainlanders visiting Singapore passed one million for the first time in 2006, according to the Singapore Tourism Board. Last year, 937,000 visited the city state and spent an averave of S$1,494 each.

Stringent laws mean money laundering is less of a concern in the Lion City. Gaming analyst professor Zeng Zhonglu, of Macau Polytechnic Institute, said Singapore exercised rigorous oversight of high rollers' gambling, in part to protect its reputation as an international financial centre.

He said the city state's tough laws would deter many high rollers from the mainland and elsewhere. 'VIP gamblers normally don't want their identities known,' Zeng said.

'The complex disclosure rules are bound to lower their interest.'

In Singapore, junket agents, the middlemen who bring high rollers to casinos, are required to disclose detailed information about themselves and their players.

High rollers must disclose their names, home addresses, passport numbers, and the value of all free amenities received from the casino or junket operators.

Operators must give detailed financial information about themselves, foot the bill for background checks and submit to finger and palm printing.

Casinos planning to host junket players must provide Singapore's Casino Regulatory Authority with a report five days in advance of a trip that details its agreement with the junket organiser.

Casinos must lodge an arrival report with authorities at least an hour before play begins, listing each player's name and biographical data.

Marina Bay Sands opened 963 of its 2,560 hotel rooms, a casino with more than 600 tables and 1,500 slot machines, convention facilities and parts of its shopping mall.

The Singapore casino market operates under a duopoly comprising Sands and Malaysia's Genting Group, which opened its Resorts World Sentosa resort in February.