Boeing 737-800 jets used by two Hong Kong airlines have been inspected to ensure there are no fuel leaks, according to the Hong Kong Civil Aviation Department.

The department had contacted both Hong Kong Express and Hong Kong Airlines after the Okinawa fire incident.

According to Kyodo News agency, Taiwan authorities believe a fuel pipe leak caused the fire.

Japan and Taiwan are conducting further inspections to determine whether the leak was the result of faulty maintenance or structural abnormalities.

A department spokesman said it is awaiting full reports from the Japanese authorities and Boeing before deciding if further steps need to be taken to ensure the aircraft is safe.

Hong Kong Express uses only 737s, three of which are 737-800s. The airline has stepped up its maintenance measures before takeoff and after landing.

Its flights were slightly delayed on August 21, with delays ranging from 30 minutes to two hours. It flies to mainland destinations such as Chongqing, Chengdu and Ningbo.

Hong Kong Airlines said its six 737-800s are in service and that no additional maintenance has been scheduled. "Our planes are only one year old, whereas the plane that burned was five years old," a spokeswoman said. The airline said no passenger has withdrawn from flights using the 737-800s.

Boeing said it will provide technical assistance to the Japanese authorities.

The eight Hong Kong passengers on the ill-fated China Airlines plane could not be reached on August 21.

Daiei Travel Services, the Taiwanese agency behind the tour, said the trip was continuing and that the Hong Kong tourists were staying at a seaside hotel.