Chinese parents spooked by a series of food safety scandals are importing baby formula from overseas in a trend that is causing milk powder supplies to dwindle across the globe.

Paranoid parents are tapping into China's massive diaspora, asking family and friends living abroad to send milk powder and baby food. Those without international connections are paying courier services to buy and send the products to China.

But now Chinese expatriates in Britain and the United States say they are finding it increasingly difficult to find supplies to send home, and medical experts are warning there could be dangers in importing an unknown international product.

Zhou Ying, who lives in New York, said she is asked to bring baby formula every time she visits China.

"One time I brought 12 cans for my friend who just had a baby," she said. "I went to five stores to buy them because each store, such as CVS or Duane Reade (two chain pharmacies), only had two or three cans."

Demand is so high in some international cities with a high concentration of Chinese expatriates, that some retailers have started imposing limits on the number of cans customers can buy.

An online Chinese trader who wished only to be known as Ukbabee, told China Daily she sells 400 cans of baby powder a month. The 52-year-old's store is one of more than 1,500 on Taobao — a Chinese online marketplace — that sell imported milk powder.

But Ukbabee said her daughter, who lives in London, was finding it increasingly difficult to find supplies, with Tesco and Boots, two major British chain stores, introducing limits for customers.

"Supplies are always short. Sometimes, my daughter has to visit two supermarkets to buy just six cans," Ukbabee said.

In response to the growing demand, a number of mailing companies across the globe, particularly in the US, are offering to buy and send milk powder to China.

Fan, who declined to give her first name, is the manager of HC Express in Flushing, a Chinese community in the New York borough of Queens. She said her business has been growing steadily since opening in 2010.

"We provide a service for buying and mailing milk powder to Chinese customers," Fan said. "They just give an order by phone and we will ship them the product. "Although the cost of shipping has been rising, orders from China keep increasing."

Kevin Tan from AAE Express Soho, also in Flushing, said a large number of their orders from the Chinese mainland are for milk powder.

But some medical experts have expressed concern, saying foreign milk powder may not be suited to the Chinese diet.

Zhang Silai, former head of pediatrics at Beijing Hospital of Integrated Traditional and Western Medicine, said there are many risks with imported milk powder, especially buying through traders who may send a product that has spent a long time in storage.

Zhang said milk powder produced and sold in foreign countries was developed to suit that marketplace, and may not be suitable for Chinese babies.

"I suggest parents buy brands sold in China because they have added some nutritional components suited to our eating habits and physical features," Zhang said.

"Milk powder sold in Japan has a lower portion of some omega-3 fatty acids because they eat a lot of seafood, but Chinese babies need it," she said.

Several large foreign companies that produce infant and toddler formula, including Nestle and Wyeth, have built factories in China to start production of milk powders for the domestic and foreign market.

Zhang said the increase in local production by multi-nationals could ease the demand for imported milk powder.

"Because Chinese parents can buy these brands in their local markets, the supplies for other countries will be increased," Zhang said.

The pediatrician said more should be done to encourage mothers to breast-feed.

"Companies should set up special rooms for working mothers to express their breast milk," Zhang said. "Breast milk is good for babies' health and will reduce the consumption of milk powder."

Wang Dingmian, former vice-chairman of the Guangdong Dairy Industry Association, said Chinese parents are highly dependant on milk powder and more should be done to encourage breast-feeding.

Contact the writers at zhengjinran@chinadaily.com.cn and jingshuw12@chinadailyusa.com