The President of Nicaragua attacked “hateful putschists” who, he said, tried to overthrow him, and seems to have ruled out early elections in a defiant public address.

Daniel Ortega’s speech came as opposition leaders prepared to increase pressure on the former revolutionary hero with three days of protests.

Addressing a pro-government rally on Saturday in the capital, Managua, the 72-year-old blamed the unrest on criminals, murderers, torturers and terrorists he accused of conspiring to seize power. He has been the target of an 11-week student-led uprising.

“Nicaragua had been progressing, had been advancing, had been growing economically, with peace and security,” Ortega told followers, according to a transcript of his speech published by the pro-government outlet Barricada. “These crimes must be stopped.”

Ortega, who was democratically elected in 2006 but is accused of ruling in an increasingly authoritarian manner, claimed he was engaged in “a fight for peace” and for the people.

However, human rights activists point out that many of the 300-plus people killed since the revolt began on 19 April were gunned down by Ortega’s own security forces or shadowy paramilitary gangs with ties to his government. The victims have included a three-month-old boy whose home was allegedly torched by masked paramilitaries and a teenage altar boy shot through the chest, also allegedly by paramilitaries.

On Friday, protest leaders – who are demanding that presidential elections currently scheduled for 2021 be brought forward to next year – announced they would ratchet up pressure on Ortega with three days of demonstrations and a second nationwide strike, starting on 12 July. “We will not abandon the streets because the streets belong to the people,” student leader Francisco Martínez told reporters.

Speaking to the Guardian last week, a member of Ortega’s inner-circle refused to rule out an early election and insisted there was “nothing that cannot be put on the table”.

However, Ortega appeared to contradict that claim in his speech on Saturday. “Here the rules are set by the constitution of the republic … You can’t just change them overnight because the idea occurred to a group of coup-mongers,” he said.

Tim Rogers, a US journalist and veteran chronicler of Nicaraguan politics, described Ortega’s speech as “a masterclass in cynicism” and accused him of “projecting all his crimes onto Nicaragua’s opposition” in a bid to escape responsibility for the bloodshed.

Ortega’s intransigence and renewed violence on Sunday morning, “do not augur well for the next 10 days,” Rogers added in a post for Nicaragua Dispatch.