The signatures will be added to a new long-term contract for Interlagos’ formula one race next month, Sao Paulo mayor Fernando Haddad claims.
Recently, F1 chief executive Bernie Ecclestone warned that Brazil will be scratched from the calendar if organisers fail to upgrade the ageing Interlagos facilities.
Mayor Haddad responded by insisting he had sent a letter to the FIA, assuring that the upgrade will be done.
And Ecclestone said in Bahrain: "I’ve just received a letter from the mayor and he’s guaranteed to revamp the whole facilities there, which will be good, we’ve been waiting long enough."
Haddad is now quoted by Brazil’s Lance: "In May, we will conclude the contract so that formula one stays here until 2020.
"We just need to go through the paperwork. It was a long discussion, it’s just that we could not commit to something that we could not do.
"It is a big job. We require a long-term contract, because we will invest more than $100 million and we could not do that without the security (of a contract).
"It is reasonable that the agreement goes to 2020," he added.