Vitaly Petrov, after visiting his regular Polish teammate in hospital, named veteran Heidfeld alongside Bruno Senna and Tonio Liuzzi as the leading contenders to race in Kubica's place this year.

"With respect for Robert, we believe it is currently not appropriate to speculate," Heidfeld's manager Andre Theuerzeit told the German news agency SID.

33-year-old German Heidfeld, with more than 170 grands prix under his belt, was Kubica's teammate at BMW between 2006 and 2009.