Singapore Airlines has taken the unusual step of publicly asking passengers on its new Airbus A380 plane not to engage in any sexual activities.

The potential problem has arisen because the first class area of its giant superjumbo contains 12 private suites complete with double beds.

Singapore, which is the first airline to start flying the A380, said the suites were not sound-proofed.

It said it did not want anyone to offend other travellers or crew.

Singapore added that while the suites were private, they were also not completely sealed.

"All we ask of customers, wherever they are on our aircraft, is to observe standards that don't cause offence to other customers and crew," the airline said in a statement.

"Nothing different applies for our Singapore Airlines Suites customers."

Singapore Airlines took delivery of its first A380 earlier this month, with the first services between Singapore and Sydney starting on 25 October.

It is now set to take delivery of a further five A380s in 2008, out of its order of 19.