Brazil's left-wing President Luiz Inácio Lula da Silva vetoed a law dramatically reducing the prison sentence of former far-right president Jair Bolsonaro, convicted last year of plotting a coup.
Mr Lula vetoed the law adopted by Congress late last year on the third anniversary of major riots by Bolsonaro supporters in the capital Brasilia over his defeat by Mr Lula in 2022 elections.
Brazil's leader had made no secret of his plan to strike down the legislation, which reduces Bolsonaro's jail sentence from 27 years to a little over two.
However, Brazil's conservative-dominated Congress has the last word and can in turn reject his veto.
Bolsonaro, 70, began serving his sentence in November.
The Supreme Court rejected his appeal to serve his sentence under house arrest, on health grounds.
Under current rules, Bolsonaro is expected to serve at least eight years behind bars.
He was convicted over a scheme to stop Mr Lula from taking office after his razor-thin loss in a bitter 2022 election that highlighted stark political divisions in Brazil.
The plot allegedly involved a plan to assassinate Mr Lula, his vice president Geraldo Alckmin and Supreme Court judge Alexandre de Moraes.
Prosecutors said the scheme failed because of a lack of support from the Brazilian military.
