The MTR Corporation on Friday said it has inspected and cleaned one of its trains after an online photo showed a suspected bed bug travelling on the Airport Express.

The photo went viral online, with some people describing the alleged bed bug as "horrible" and "terrifying".

Others, however, said they thought it was "only a matter of time" before bed bugs arrive in Hong Kong, with reports of outbreaks in other places.

The railway company said a passenger alerted it to the presence of the suspected bed bug at about 9pm on Thursday, but the creature was nowhere to be found.

The MTR assured passengers that the train was thoroughly inspected and had undergone high-temperature cleaning.

It said it will strengthen inspections and cleaning, especially on trains with non-metal seats, and pest control work will be carried out on Airport Express, Disneyland Resort Line and high-speed rail trains, as well as in the first class carriages of East Rail Line trains.