Cape Town - Liberty Media needs to look at other avenues for generate income for Formula 1 with Toto Wolff stating that current hosting fees are not sustainable. 

Last year Silverstone activated a break clause to cease hosting the British Grand Prix race after 2019, citing finances as the reason. 

That, though, is not the only race under threat. 

Hockenheim have also stated that they "cannot continue" with the current conditions of their contract as they are taking huge financial losses. 

Wolff agrees these deals are not working for the circuits. 

"Sanction fees were one of the three key revenue generators in the old Bernie Formula One business model. And he was exceptional at these deals," the Mercedes boss told Reuters. 

"I am not sure that is sustainable. 

"It is clear that when there is a change of regime, people and promoters will negotiate and try to restructure the business model. 

"Bernie was squeezing the last cent out for the benefit of the shareholders and the teams but it left certain promoters in a very difficult economic situation." 

The Austrian says it is up to Liberty Media to explore news avenues for generating income for Formula 1. 

He added that "maybe that one pillar (hosting fees) is going to be difficult to maintain on the levels we have seen before. 

"We have to grow in other areas, we have to grow broadcast deals and digital revenue and monetise alternative revenue streams." 

While broadcast deals and advertising make up the other two parts of the Bernie Ecclestone model, Liberty have also began to tap into the digital market with F1 streaming.