EADS co-chief executive Noel Forgeard said on Friday he first knew in April of potential production problems on the Airbus A380 but ruled out resigning over the issue which triggered an EADS stock collapse this week.

Under fire over what Airbus parent EADS told investors and his own decision to sell stock in March, shortly before the group veered into what its chairman has called a "major crisis", Forgeard said the scale of problems had not been clear at first.

"The problems of delays were put on the table during April and at the end of May many people still thought it was possible to resolve them," Forgeard said on Europe 1 radio.

"The detailed work reached its conclusions on June 13 and we published them on the same day."

Investors stripped a quarter of the value off EADS, Europe's biggest aerospace group which owns 80 percent of Airbus, on Wednesday after the planemaker said wiring problems had pushed back deliveries of its A380 superjumbo by six months.

It was the second such delay in a year and came alongside a EUR2 billion (USD$2.52 billion) profit warning spread over four years as Airbus acknowledged it would take until 2010 to recover.

EADS has launched an investigation into the delays which followed Airbus assurances in May that the EUR12 billion (USD$15.2 billion) program to build the world's largest airliner was on track.

German Economy Minister Michael Glos urged the Franco-German-led company to resolve the problems quickly and German regulator BAFIN said it was studying EADS share trading.

French shareholder activists have also called for an inquiry by France's regulator AMF into share dealings by Forgeard and others in March, shortly before its core French and German industrial shareholders reduced their stakes.

Forgeard said he was among six senior EADS executives who had exercised options or sold stock up to March 17.

He said it was three days later on March 20 that he had learnt that core shareholders Lagardere and DaimlerChrysler had decided to reduce their stakes, and in April that he first heard of A380 wiring snags.

A spokeswoman for the AMF said it would not comment on whether it had launched or would launch a probe.

Regulatory filings show that Forgeard made EUR2.5 million (USD$3.2 million) from the sale of 162,000 shares from 2002-03 stock option plans on March 15. But on March 9 he also bought 131,000 shares by exercising previous 2000 and 2001 stock option plans.

Small shareholder group France Petits Porteurs called on EADS to return any executive share profits and said its leaders should either be sacked for not knowing what was happening inside the factories or jailed for insider trading.

Forgeard dismissed the growing furore and said he had nothing to fear from any inquiry into insider trading.

Insider trading carries a maximum prison sentence in France of two years and a fine of at least EUR1.5 million (USD$1.9 million), stretching up to 10 times the illegal profits, said Jerome Herbert, a securities lawyer at Winston & Strawn in Paris.

Forgeard said Airbus would recover from the production problems, which involve the A380's 500 km of wiring and have now delayed most deliveries of its A380 superjumbo by a year.

He repeated that Airbus would announce an improved version of its A350 mid-sized twinjet next month to redress a gap in sales with US rival Boeing.

Aviation analysts say it is this jet -- aimed at a market of thousands of potential sales in coming decades rather than the hundreds seen for the A380 -- that will be decisive for Airbus.