Peruvian opposition leader Ollanta Humala has been charged with rebellion in connection with a 2005 siege at a police station in which six men died.
Ollanta Humala was initially charged with being a witness
He is accused of helping to mastermind the siege, which was led by his brother Antauro to demand the resignation of the then President, Alejandro Toledo.
Mr Humala, an ex-army officer, denies any wrongdoing. He remains free on bail but is not allowed to leave Peru.
Earlier this year, Mr Humala lost the presidential election to Alan Garcia.
Mr Humala's political spokesman, Carlos Tapia, said the courts were being used to carry out campaigns of political persecution.
Mr Toledo - who faces criminal charges in an unrelated case - was also being persecuted, he added.
Mr Humala was in South Korea when, on 1 January 2005, his younger brother along with more than 150 army reservists stormed a remote police station 443km (275 miles) south-east of the capital, Lima.
Four policemen were killed as well as two of the rebels.
Around the time, Antauro Humala, a former army major, was shown on video saying his brother had chosen the site of the insurrection.
While Antauro was jailed and charged with rebellion, kidnapping and homicide, Ollanta was initially charged with being a witness.
On Wednesday, an official from the prosecutor's office confirmed that a judge had filed charges of rebellion against him.
If convicted, he could face up to 20 years in jail.