PRIVATE hospital charges have rocketed this year by up to 30 per cent - almost twice as much as the maximum rise in private surgical fees, according to a recent Medical Insurance Association survey. The association is urging companies to review their medical insurance coverage for employees in the light of the increases, saying that otherwise employees could be faced with having to cover ''extremely high'' shortfall payments themselves. The association surveyed its members in July on the level of claims submitted by doctors for surgery performed between January and June this year. It found surgical fees were between nine and 18 per cent higher than those claimed last year, while some hospital charges rose by up to 30 per cent. Medical Insurance Association chairman Nicholas Donne said this was not an across-the-board increase. Some hospitals had raised room and board fees by only 10 or 11 per cent, but others had increased them by up to 30 per cent. This was particularly true of private bed charges, he said: ''Some hospitals grade them - a luxury room with one gold tap, two gold taps, three gold taps - and charge accordingly.'' Arthur Wong Sau-yin, planning and marketing director for the Hong Kong Adventist Hospital - which has raised fees by about 11 per cent - said one reason for the increase was high staffing costs due to the shortage of qualified nurses. Medical Insurance Association manager Eric Lee Wing-po said surgical fees were rising more slowly than hospital fees because of more competition between doctors and more knowledgeable patients. Hong Kong Medical Association spokesman Dr Lee Kin-hung agreed, adding that hospitals were also coming under pressure from rising technology costs. He said an association survey earlier this year found that surgical fees had dropped 17 per cent for major operations or remained the same for minor surgery. Mr Lee said the Medical Insurance Association felt it had a duty to warn employers of the situation because many companies had decided not to increase the level of medical insurance coverage provided to employees. In many instances, employees were unaware that the level of medical cover provided was relatively low - meaning it was highly likely that they would be faced with a nasty shock when they saw their medical bill. Mr Lee said it was difficult to say how big a shortfall an employee might be faced with as it depended on the amount of insurance premium, the type of surgery and the class of hospital accommodation. Mr Donne said if employers felt they could not increase their insurance premiums, they should at least warn employees there might be a shortfall problem. This would enable employees to ensure they did not incur medical expenses that would not be covered. The Medical Insurance Association has released a list of suggested minimum levels of cover. It says insurance policies should provide at least $1,200 per day for a private room; $600 for a semi-private room; and $300 for a ward bed. The same amount should be provided each day for the attending physician fee, which tends to reflect the room charge. It says a scale of $10,000, $6,000 and $3,000 should be provided for hospital expenses - such as laboratory examinations, injections and dressings - for the different classes of room. Surgical fees also varied according to room class. Cover for a major operation for the different classes should be $25,000; $20,000 and $15,000. Anaesthetists generally charged 25 to 30 per cent of the surgeon's fees, while operating theatre charges were usually set at about 25 per cent, the association said.