By Alan Baldwin

BARCELONA (Reuters) - Michael Schumacher has denied frustration lay behind his criticism of Formula One tire supplier Pirelli and said he was happy to have opened a wider debate about where the sport was heading.

The seven times world champion has said the characteristics of the tires had forced drivers to be more strategic and manage the rubber rather than being able to race flat out every lap.

"They are so peaky and so special that we don't put the cars or ourselves to the limit," he had complained after a test in Italy last week.

"We drive like on raw eggs and don't want to stress the tires at all," added the 43-year-old German.

The Mercedes driver told reporters at the Spanish Grand Prix on Thursday that he wanted to open a broader debate about "the principle of how Formula One should be.

"I am quite happy that we have initiated a discussion about how much influence one or another part should have in Formula One," he added.

"It is certainly nothing to do with me being 'frustrated' because I haven't really been frustrated. I did a good race (in Bahrain) and came from 22nd and finished 10th which I think was a positive result."

Schumacher, winner of 91 races and the most successful driver in the history of the sport, has not been on the podium since he started his comeback with Mercedes in 2010.

"It's nothing to me, it's a general discussion that I wanted clearly to start to happen," he said.

Schumacher won his last five titles at Ferrari with Bridgestone, who were particularly close to the Italian team, at a time when races were more like a series of flat-out sprints between pitstops.

The Japanese manufacturer quit the sport at the end of 2010 and Pirelli returned as sole supplier.

The Italian tires are very different, with Pirelli saying they were asked to make sure they degraded more quickly to liven up racing and add another strategic element to the mix.

With drivers having to use two different compounds in a race, and their pace slowed by wear at different stages of the grand prix, there is now a premium on tire management.

(Reporting by Alan Baldwin, editing by Ken Ferris)