Humberto Ortega, the ex-head of Nicaragua's military, has called on his brother President Daniel Ortega to stop the pro-government paramilitaries that are blamed for months of deadly unrest.
The government must act responsibly to "end the presence of these armed people", said Humberto Ortega in a TV interview with CNN En Español.
President Ortega has defied calls to stand down and blamed the opposition.
More than 300 people have died during three months of protest in the country.
President Ortega, 72, gave a rare interview to US news channel Fox earlier this week to address the crisis. He said the paramilitaries were funded by opposition MPs and drug cartels, but he provided no evidence of the alleged links.
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His 71-year-old brother - a former defence minister and stalwart of the Sandinista revolution - said the paramilitaries act "as if they are a military or police authority". He urged the president to work with the army to resolve the situation.
In July, he published an open letter, making a similar plea and calling for the election to be brought forward.
Doctors sacked
More than 40 medical staff have been sacked for treating wounded anti-government protesters in the city of Leon, it was reported on Friday.
Doctors, nurses and technicians are among those who lost their jobs at a public hospital.
The protests - which began as a stand against pension reform - have escalated since April, turning into a broader call for the president to resign.