Hockenheim officials have warned that they cannot wait forever for Formula 1 to decide if the German venue will be added to the 2020 'corona calendar'.

Baku, Singapore and Suzuka have all now been officially cancelled, triggering F1 sporting boss Ross Brawn's plan to replace them with more European events.

Some of the potential replacement venues are not active F1 circuits, including Imola, Mugello, Hockenheim and Portimao's Algarve track in Portugal.

"We confirm that negotiations are underway with Formula 1," a spokesman for the Portuguese venue confirmed.

But Hockenheim chief Jorn Teske told DPA news agency that the former German GP venue cannot wait forever for F1 to decide.

"It is nothing new to say that the later a decision is made, the more difficult it becomes," he said.

Another circuit spokesman told RTL that it is currently "only speculation" that the European calendar for 2020 will be expanded.

"The same is true of whether a race would then take place at the Hockenheimring," the spokesman added.

Jochen Nerpel, another Hockenheim official, said: "Upon request, we will be happy to check the feasibility.

"But we cannot keep any unconfirmed dates for Formula 1 over a matter of several weeks," he added.