FORMER US Democrat presidential nominee Bernie Sanders has sent a letter signed by 29 US politicians to Brazil’s ambassador in Washington demanding the release from jail of former president Luiz Inacio Lula da Silva.

The letter denounces the “highly questionable and politicised” sentencing of Lula, saying it was based on “unproven accusations.”

The politicians said that the former president, who has been jailed for 12 years on corruption and money-laundering charges, should be released immediately.

Mr Sanders and the letter’s other signatories blast the right-wing administration of unelected president Michel Temer over its cuts to social programmes and employment rights, warning of “intensifying attacks against democracy and human rights in Brazil.”

The letter says: “The fight against corruption should not be used to justify the persecution of political opponents or deny them the right to participate in free elections.”

Lula is one of Brazil’s most popular politicians, having left office in 2011 with an 83 per cent approval rating. He remains ahead in almost every opinion poll for October’s presidential election.