The concentration of foreign patients in these hospitals is very high.

Oh, yes, said the guide, there is a foreign patients' clinic at the big hospital here in Beijing.

Leading American medical centers already market themselves abroad to recruit foreign patients to travel for operations.

"The average for foreign patients, who usually come for much more serious problems, is $20,000 to $30,000," he said.

The Internet is another channel being mined for foreign patients.

Today, many American hospitals cater to foreign patients, including government officials and their families.

This is particularly important in Belgium, a small country with a relatively large inflow of foreign patients.

In any case it might not do much good for frail foreign patients to come for treatment.

As of 2013, the city receives up to 200 foreign patients every day.

However, there are no consolidated statistics about the number of foreign patients that the city receives.