Peter Sauber has refused to comment on reports Pedro de la Rosa will not return to the wheel of his car for the rest of the 2010 season.

The authoritative Blick newspaper, well-connected with the Hinwil based team's 66-year-old founder and boss, said Nick Heidfeld will be driving the sister C29 alongside Kamui Kobayashi in Singapore in two weeks and beyond.

La Nueva Espana said that after Spaniard de la Rosa's post-race media rounds in the Monza paddock on late Sunday afternoon, the 39-year-old was called for a meeting with the team's management.

The report said the driver left the circuit immediately afterwards "with a scowl" and began his road journey back to his home in Zurich.

"He did not answer his phone," said the writer.

Peter Sauber also refused to comment: "I am not talking about my drivers," he said.

After not appearing in the Spa paddock two weeks ago, Heidfeld was inconspicuously present at Monza over the race weekend.

The report at lne.es said sources have confirmed that it is "99 per cent" certain the 33-year-old German will be racing in de la Rosa's place in Singapore.