Saturday 30 January at 04:01 : Jan.30 (GMM) Ferrari is concerned the double diffuser legality controversy in formula one may be set to re-fire.

At the launch of the F10 on Thursday, technical director Aldo Costa said he thought at least one team was "on the limit" of legality with its 2010 design of the rear aerodynamic solution.

The initial emergence of double diffusers on the Brawn, Williams and Toyota cars last year caused great controversy, until the FIA said their rule interpretation was in fact legal.

"We were put in a very unpleasant position last year and we still think that the double diffuser is illegal," Costa told La Gazzetta dello Sport. "Maybe the saga will just carry on."

Ferrari's chief designer Nikolas Tombazis admitted: "The double diffuser allows a lot of room for experimentation and this is what worries us."

By the time of the McLaren launch on Friday, rumours were circulating that 2010 cars would be debuting 'triple' and 'quadruple' diffusers.

"We've got a fairly extreme incarnation (of double diffuser), but we won't be alone in that -- we believe we will see some pretty extreme solutions from our competitors as well," McLaren's engineering director Paddy Lowe said.

On the launch stage, the rear of McLaren's MP4-25 was tucked into a corner, and the diffuser itself was apparently covered.

All three 2010 cars seen so far - the Ferrari, McLaren and Williams - feature very high noses, to allow maximum airflow to much bigger diffusers.

Lowe denied Ferrari's fears that the diffuser rules are still unclear.

"We think the interpretation is very clear," he said. "In certain aspects we have sought guidance from the FIA and they have come out with very clear interpretation, understanding and guidance -- and we think that has been made available to all the teams.

"We are hoping for a much cleaner start to the season then we had a year ago in terms of the teams' collective understanding of the basis from which we go racing," Lowe added.