HONG KONG, Oct.13 (Reuters) - Trucks from mainland China pull up in the dead of night at a sprawling warehouse complex to the north of Hong Kong, boxes are unloaded and samples taken.

In a world where deadly food scares are increasingly regular occurrences, Hong Kong is taking no chances with produce arriving from its giant Communist neighbor.

The food safety center at the ParknShop supermarket chain is in the frontline of the battle to protect consumers.  China is not the only potential source of danger, but the experts here are well aware of risks posed by cargoes from specific origins.

"There are issues for food from China," Peter Johnston, the quality assurance manager at ParknShop, told Reuters.

"Pesticide in Chinese vegetables is an area which is a particular problem," Johnston said. "If you eat some contaminated vegetables, you can end up in hospital or even worse.  It has happened and generally it happens every year."

Chinese food safety standards were once a largely domestic issue as the country's produce was not so widely exposed to international markets, but the country's goods are now much more visible on Western supermarket shelves.

And Beijing's entry to the World Trade Organization (WTO) late last year will open doors further to the global marketplace.

China's food exports, often very competitively priced, include fresh and processed fruits, vegetables, seafood and meat.

One of the main international concerns is over the use of antibiotics for livestock, poultry, and seafood.  Earlier this year, Russia banned imports of US chicken and turkey, citing health concerns over antibiotics in feed and fears of salmonella.

China was involved in a similar scare early this year after the antibiotic chloramphenicol - which can cause a potentially lethal form of anaemia in humans - was detected in shrimp shipped from China to Europe.

The scare affected exports from China and other Asian nations such as Thailand and Vietnam.

Despite efforts by China's government, industry officials say it is extremely difficult to control the use of potent drugs in such a vast country with some 900 million farmers and countless backyard farming operations.

Farmers often use antibiotics and other drugs to enhance growth of livestock or fish, they say.  Some also use pesticides without paying enough attention to instructions, such as keeping products off the market for a certain time after application.

The European Union (EU) has kept its door shut for more than six months to imports of certain types of fresh food from China, although it recently relaxed tough controls on some fish products.

Japan is also conducting tough inspections and considering a ban on imports of frozen spinach from China after discovering high level of pesticides.

Some industry officials and experts worry that some countries, including the EU and Japan, may be using such food safety fears as non-tariff trade barriers to limit imports of low-priced products from China to protect their own farmers.

"China firmly opposes ay protectionist and discriminatory measures taken in the guise of food safety," Jian Fan, China's deputy director at the Foreign Trade Ministry, told a news conference last month, referring to the spinach row with Japan.

A non-Chinese industry official in Beijing shared such concerns, saying the EU had been slow in reopening its market following the chloramphenicol scare and that Japanese checks on poultry were stricter than necessary since an outbreak of Newcastle disease in China last year.

"There are some very clean, efficient poultry operations here in the northeastern part of China.  The Chinese feel they are unfairly treated'" the official said on condition of anonymity. "We've also had lots of problems with Japan in particular."

Xue Yongjiu at Beijing University of International Business and Economics has predicted "green barriers" will be a major source of future disputes between China and other WTO members.

"The key to overcoming and avoiding these kinds of restrictions is to enhance farmers' standards," he told the South China Morning Post, an English daily in Hong Kong.

"The fact is that food safety and environmental management standards in China are behind international levels."

While countries like the EU and Japan have limited food imports from China, it is difficult for the territory of Hong Kong to turn away produce from the Chinese mainland.