A Managua judge issued an arrest warrant on Monday for opposition leader Felix Maradiaga, accused by the Nicaraguan government of financing violent protests that have rocked the impoverished Central American nation.
The government of President Daniel Ortega has alleged that Maradiaga financed the protests and trained protesters through a think tank he heads, the Institute of Strategic Studies and Public Policies.
"My conscience is clean. I've always been guided by justice, non-violence and integrity. Today I have more moral conviction than ever before," Maradiaga wrote on Twitter.
"Those of us who love Nicaragua and believe in liberty have the ethical obligation to continue firmly in this civic struggle," he added.
Maradiaga is currently not in Nicaragua.
About 300 people have been jailed since protests erupted in April, according to local human rights activists. More than 300 people were killed during those protests in crackdowns by Nicaraguan police and armed groups backing the government, human rights groups have said.
The protests began after Ortega's leftist government moved to reduce welfare benefits, but soon escalated into broader opposition against Ortega, who has been in office since 2007. He also held power in the 1980s during Nicaragua's civil war.
The current violence is the worst since his Sandinista government battled U.S.-backed "Contra" rebels in the 1980s.