Singapore Airlines has not ruled out grounding its entire fleet of A380s amid concerns over their engines.
Three of the airline's A380s were grounded on Wednesday in Melbourne, Sydney and London after precautionary checks on the planes.
Singapore Airlines has 11 A380s in its fleet.
Rolls-Royce, the aircraft engine manufacturer, has confirmed there are oil stains on the engines, which will be replaced.
The safety checks were done after last week's emergency incident over Indonesia involving a Qantas A380.
Singapore Airlines spokesperson Bryony Duncan-Smith says the company's eight other Airbus A380 planes are still in service, but this could change.
Qantas grounded its six A380s last Thursday after one of the plane's engines broke apart in flight, forcing the pilots to make an emergency landing in Singapore. The plane had 459 passengers and crew on board.
Meanwhile, the European Union has fined 11 air cargo carriers, including British Airways, Air France, Japan Airlines and Qantas,
US$1 billion (NZ$1.4 billion) for running a cartel.
Qantas executives have been warned they risk up to 10 years in jail if they continue to engage in cartel price-fixing practices.
The fines relate to co-ordinated action on surcharges for fuel and security within the EU zone between 1999 and 2006.
In 2008, Qantas was also fined $26 million under a deal reached with Australia's competition watchdog for the same price-fixing cartel.
The Australian Competition and Consumer Commission said on Wednesday that it regarded such conduct as criminal.
Chairman Graeme Samuel says it could push for jail terms of up to 10 years and fines of $13 million or more.
The United States Department of Justice has already charged 18 airlines and several executives in its investigation of the cargo cartel, and imposed more than US$1.5 billion in fines.