Double Formula One world champion Fernando Alonso has played down his Renault team's chances of taking on Ferrari and McLaren in next month's Australian season-opener.

The Spaniard said BMW Sauber had impressed him most of late during testing, and suggested they could be dark horses in Melbourne on March 16.

Alonso also defended his compatriots from accusations of racism after former McLaren team mate Lewis Hamilton suffered abuse from spectators earlier this month at the Circuit de Catalunya.

"We are pretty far behind," he told As. "We are not in a position to fight for anything important right now.

"Thinking about a podium (in Melbourne) would be too optimistic at the moment...today, thinking about it coldly, getting on the podium is a dream."

Alonso said Ferrari were ahead, with McLaren and BMW Sauber close behind. Renault were fighting in the next group with Williams and Red Bull.

"But everything changes very quickly in Formula One," added Alonso. "Two or three weeks ago BMW were a little bit behind, we were close to them. Now they are very close to McLaren.

"They (BMW) are going very fast. They have not shown their cards. They are running with the tank full and are doing very good times."

BMW Sauber were runners-up in 2007 after McLaren were stripped of their constructors' points for a spying controversy.

Alonso, who left McLaren after a troubled season in which he fell out with team bosses and was dethroned by Ferrari's Kimi Raikkonen, said aerodynamics remained Renault's weak point and ruled out any quick breakthrough.

He feared it would be hard, on form, for Renault to be among the first 10 in qualifying.

Asked whether he was being overly pessimistic, he replied: "No. I just want to tone down the euphoria I see in the media. As far as my spirit is concerned I feel a thousand times better than I did a few months ago."

Alonso was also critical of the governing FIA's plans to launch a 'Racing Against Racism' campaign at the Spanish Grand Prix in April.

"This is not a racist country nor are the supporters," he said. "It was an isolated case and if the FIA or whoever says Spanish fans are racist, it's laughable.

"Last year they called me a dog at some races. (Former champion) Niki Lauda said things about me and nobody said anything nor came to show me their support either," added the Spaniard, who said he had not spoken to Hamilton since the incident.

Hamilton returns to Spain next week for further testing ahead of the new season.