Bernie Ecclestone has threatened to axe Brazil's Formula 1 race if organisers fail to urgently upgrade the ageing Interlagos circuit.The F1 chief executive told O Estado de Sao Paulo newspaper that the city's November finale for the 2013 season could be its very last grand prix.Ecclestone said: "Interlagos' promises to upgrade have not been met and the relationships and feelings that I have for the race are no longer enough."'WORST ON THE CALENDAR'Ecclestone said he cannot keep pushing other circuits to improve their facilities whilst letting Brazil get away with having the worst venue on the calendar."The track is one of the best in the world, for sure. Yet the facilities for the public and for the teams are the worst on the calendar."It doesn't have to be like here (Shanghai), but it must meet our operational needs. We can't keep pushing the other tracks while Interlagos remains as it is year after year," he said.Ecclestone said the facilities are so bad at Interlagos that teams have to have meetings in the pit garages: "You don't even see that at street tracks, like Monaco, Melbourne and Montreal."He said the Sao Paulo mayor's office must honour its promise to upgrade the venue.He said: "I don't expect changes for this year but if the circuit is not in shape, then we will not go to Sao Paulo in 2014. We have to know before if we'll be in Sao Paulo or another city in Brazil."'I'M TIRED OF THE PROMISES'Indeed, Ecclestone travelled to Santa Catarina late 2012, to hear about plans for a new Hermann Tilke-designed F1 track.He admitted: "I confess to having been impressed by the willingness of these people to carry out their project. I believe that if we give them the green light, they will start work immediately.Asked if the threat to dump Interlagos is genuine, Ecclestone insisted: "We would not even use the old asterisk that (the race could take place) subject to improvements."I'm tired of the promises. I'm told the city will not have the football competition before the world cup because the stadium isn't ready."It'll be the same for formula one; no more Sao Paulo and, who knows, maybe no more Brazil because they don't have a circuit," he added.