A fully loaded food trolley weighs about 54kg. The Civil Aviation Department said food trolleys were involved in three in-flight accidents causing injury over the past three years - one each in 1998, 1999 and this year.
Dragonair and Cathay Pacific must report any in-flight injury to the department, which monitors and certifies the airworthiness of their planes.
Dragonair said no one had ever been hurt by a food trolley on any of its flights. 'We have no record of any mishap involving a trolley on our flights. In-flight safety is an important part of our normal procedures,' a spokesman said.
Cathay Pacific did not reply to questions about trolley operations on its planes.
A department spokeswoman said the design and operation of the trolleys aboard planes was covered by airworthiness regulations.
The department says extra restraints for trolleys are required to protect flight attendants as they are usually stored close to where the attendants sit during take-off, landing and rest breaks.