HONG KONG (AFP) - Hong Kong customs officials said on Friday they had arrested 64 people for unlicensed baby milk powder exports, in a move aimed to stifle the smuggling of formula before Chinese New Year.

The ongoing operation, which started Thursday, has already netted 64 people who attempted to bring a total of over 400kg of infant formula into mainland China.

Hong Kong barred people from taking more than than 1.8kg of formula out of the city in March after a rush on milk powder by Chinese parents.

Mainland Chinese are widely distrustful of domestic milk brands due to a 2008 scandal involving formula tainted with melamine that killed six children and sickened 300,000 others.

Their concern triggered demand which saw shelves emptied around the world.

With Chinese new year approaching in less than a month, smuggling activities have increased for formula, which is sometimes given as a gift, prompting authorities to take action.

"We have arrested 29 males and 35 females aged between 19 to 81 years old, and have seized 450kg of baby formula," head of rail and ferry command for Hong Kong customs Louise Ho told reporters on Friday.

Offenders face a fine of HK$500,000 (S$633,000) and two years' imprisonment.

One case had seen individuals attempt to smuggle nearly 20kg of powder, Ho said, adding that the arrested persons would have been paid HK$160 for seven tins of powder.

The traders would be most active in the mid afternoon when customs officers were changing shifts or would try to enter the gates right before they closed to lessen the chances of being inspected, she said.

"They will hide the baby powder in backpacks, in hand-carried bags or in wheeled trolleys. They would even use suitcases to store larger quantities of baby formula," she said.

Both the city and mainland customs will be stepping up enforcement actions during the period before the Chinese new year, Ho added.

A Hong Kong court jailed a woman last month for smuggling baby formula, the first time anybody has been sent to prison under the city's ban on unlicensed milk powder exports.

Although Hong Kong was returned to Chinese rule in 1997, it maintains a semi-autonomous status with its own laws and customs rules and promotes itself as a free port.

Hundreds of mainland Chinese were seen stuffing tins of baby milk powder into large bags and boxes near train stations at the border before the ban. The majority of them were parallel traders who travel to Hong Kong daily by train.