Singapore Airlines (SIA) has started the process of checking two thirds of its 15-plane Airbus A380 fleet as the European Aviation Safety Agency (EASA) warned of new cracks on the superjumbo's wings.

An spokesman for the state carrier told AFP it was instructed by the EASA to check six of its aircraft within four days, and four of its aircraft within six weeks.

"We are carrying out the checks as instructed... We are already inspecting one of our aircraft as a precautionary measure," an SIA spokesman told AFP.

"The safety of our customers and crew is our number one priority and we will ensure that we take whatever action is needed for the continued safe operation of our A380 fleet."

SIA's checks come as the EASA on Friday recommended checks on 30 out of 67 A380s in service around the world after new cracks were discovered in the superjumbo's wings.

"Following an unscheduled internal inspection of an A380 wing, some rib feet have been found with cracks originating from the rib to skin panel attachment holes," the EASA said in a directive.

"Further to this finding, inspections were carried out on a number of other aeroplanes where further cracks have been found. During one of those inspections, a new form of rib foot cracking originating from the forward and aft edges of the vertical web of the rib feet has been identified."

"This condition, if not detected and corrected, could potentially affect the structural integrity of the aeroplane," the directive added.

The checks are more urgent the more flights a plane has made and a source close to the matter said they were required on nine out of 67 A380s in service around the world within four days and on 21 others within six weeks.

This is the second time in barely two weeks that Airbus has found cracks in the A380's wings.

The aeroplane manufacturer had revealed on January 5 that "minor cracks" had been found on some A380s, but said they posed no safety problem and recommended a way they could be fixed.

Korean Air said Saturday it had found no cracks on all its five Airbus A380s but it would carry out further detailed checks on them if requested to do so.

"We've found no cracks on the planes but we're waiting for detailed instructions from EASA or the manufacturer," a spokeswoman at Korean Air told AFP.

"We would carry out microscopic checks if we're told to do so," she added.

Korean Air currently operates five A380s on routes between Seoul and Hong Kong, Tokyo, Los Angeles and New York.

It plans to introduce five more of the world's biggest passenger jet by 2016.