Ryanair has been offered up to 600 aircraft since placing an advertisement early last month.

It is seeking second-hand Boeing 737-800s, 737-300s or 737-400s, its commercial director Mr Michael Cawley said yesterday.

Many of the aircraft have come on to the market at reduced prices since the September 11th terrorist attacks on the US and the subsequent announcements of cutbacks by airlines worldwide, he said.

"It is a softening market. Nobody has come along and offered a price and revised it downward subsequently, but you can see a general trend where more recent offers are much weaker than the previous ones," said Mr Cawley.

"Demand for aircraft is weak. Airlines are getting rid of aircraft. Leasing companies have aircraft on their hands and we are one of the few companies expanding in this situation. There are more sellers than buyers, so the price is bound to fall."

The low-cost airline is seeking to buy up to 50 second-hand aircraft. Reports said that Ryanair could acquire aircraft for as low as $11 million (€11.9 million) each. When it placed the advertisement in August, industry sources had said the aircraft could cost between $13 million and $40 million.

Mr Cawley declined to comment on the price range of the aircraft it had been offered.