An exiled Rwandan general accused President Paul Kagame on Sunday of abusing an anti-graft drive to frame his opponents in the central African country which holds presidential elections in August.
Lieutenant-General Faustin Kayumba Nyamwasa fled to South Africa earlier this year after falling out with Kagame in what regional analysts see as a growing rift between the president and top aides in the party and army.
"If accountability is going to be used as a political weapon to frame perceived opponents, then it ceases to be meaningful or useful," Nyamwasa said in a statement printed in the Ugandan newspaper the Monitor on Sunday.
Neither the president's office nor the government spokeswoman were immediately available for comment.
The country's ombudsman, Tito Rutaremara, denied the allegations and said the war on graft, which has earned Rwanda plaudits from donors and watchdogs, is independent of political interference and integral to the nation's development.
Analysts say the flight of Nyamwasa, who fought alongside Kagame to end the 1994 genocide, the arrest of two other senior officers and a military reshuffle are signs of a growing rift a between the president and top aides.
U.S. Assistant Secretary of State for African Affairs Johnnie Carson said last week that the Rwandan government had taken "a series of worrying actions".
In the run up to polls, Rwanda has suspended two independent newspapers, arrested a high-profile opposition figure, expelled a human rights researcher and prevented two opposition parties from registering, Carson told the U.S. Congress.
Rwandan authorities link Nyamwasa and another fugitive senior officer in South Africa to a series of deadly grenade attacks in the capital this year and accuse him of nepotism, divisionism and the "primitive accumulation of wealth".
Nyamwasa rejected the charges and accused the president of hypocrisy over his zero tolerance stance on corruption.
"(He) should explain to the party and to the people of Rwanda why he heads a party without a treasurer and how much money the RPF (Rwandan Patriotic Front) has since it owns all the biggest companies in the country and contributions of party members," Nyamwasa said. "In Rwanda, President Kagame is the institutions."
Rutaremara said Nyamwasa was himself corrupt and should accept that he had made mistakes.
Transparency International labels Rwanda the least corrupt country in the region, while the World Bank said it was the best global business reformer in 2009.