Hong Kong moved Friday to stop people crossing into mainland China with large quantities of baby formula due to fears of shortages in the city before the Lunar New Year.

Formula is popular with mainlanders because of concerns about the safety of food processed in China following a series of scandals, notably in 2008 when six babies died from drinking milk tainted with the chemical melamine.

The new measures would stop people from taking more than 1.8 kilograms (four pounds) of formula across the border, in a bid to crack down on the so-called "parallel traders" who sell the milk powder at a profit in China.

"To combat the movements of the parallel traders, the government will amend the import and export general regulations," Health Minister Ko Wing-man told a news conference.

Ko said he would seek cabinet's approval for the amendment this month.

Other measures include tighter border restrictions for mainland Chinese visitors who enter the city more than once in a day and strict luggage weight restrictions on trains.

Hong Kong media this week broadcast images of mainland visitors stuffing tins of milk powder into large bags and boxes near train stations at the border -- most of them thought to be traders who dodge import tariffs on their return.

Although the former British colony was returned to Chinese rule in 1997, it maintains a semi-autonomous status with its own laws and immigration controls.

Friday's announcement came after supporters of tougher restrictions on milk powder exports appealed to US President Barack Obama in an online petition labelled "Baby Hunger Outbreak in Hong Kong, International Aid Requested".

The appeal on the "We the People" section of the White House website drew more than 13,300 signatures.

"We request for international support and assistance as babies in Hong Kong will face malnutrition very soon," it said.