Managua (AFP) - Nicaraguan President Daniel Ortega on Friday accepted conditions of the country's bishops to initiate dialogue after protests that left dozens of people dead.

"We agree to work on each of the points raised (by the bishops), taking into account that all of them reflect their good will as mediators and witnesses," Ortega said in a letter to the Episcopal Conference of Nicaragua.

"We are all ready to attend your call for dialogue at the earliest possible date, for the peace of all Nicaraguans," the letter said.

Among the bishops' conditions are the cessation of repression and the entry of the Inter-American Commission on Human Rights to investigate deaths that occurred during anti-Ortega protests.

In the letter, the president said he agreed with the bishops on "the necessity of ceasing the violence, intimidation and aggression against citizens."

A wave of protests began in Nicaragua on April 18, triggered by an aborted attempt to reform the near-bankrupt social security system, but quickly expanded to include a wave of grievances against Ortega, including claims of corruption and repression.

The brutality of the repression by security forces, and arbitrary arrests of protesters, has sparked national outrage and fuelled protests across the Central American nation.

On Wednesday, tens of thousands rallied against the government.

The protests pose a serious challenge to the authority of Ortega, 72, who has ruled Nicaragua for the past 11 years and before that from 1979-1990.

The United Nations rights office on Friday asked Nicaragua to allow it to carry out an investigation into "credible" reports that at least 47 people, most of them students, have been killed since the series of protests began.