UNITED NATIONS (AP) — Venezuelan diplomat Isaias Medina said he resigned because of the systematic persecution of civilians, "state terrorism" and violations of the constitution by President Nicolas Maduro's government — and he said Maduro should resign too.

Medina, an international lawyer who was a minister counselor at Venezuela's U.N. Mission, told The Associated Press on Thursday night that the last 100 days, which have left more than 15,000 people injured and over 100 dead, "made a huge impact on me."

He said he decided to resign "based on principles" because "it would be hypocritical to remain here not representing what the values of the U.N. Charter are."

And he had a message for Maduro: "Leave the office so that a new government can take place and do their job."

"This is a failed state," Medina said. "This is a fugitive government and a complete dictatorship. ... Maduro does not have the right to be in that office."

Rafael Ramirez, Venezuela's U.N. ambassador, rejected Medina's remarks and said the diplomat had been fired.

"I condemn the conduct of Isaias Medina. We have immediately relieved him of his duties. He does not represent us. He has acted in a dishonest manner," Ramirez said in one of two Thursday evening tweets on the matter.

Medina said he worked as a lawyer, including in New York in the 1990s, and had been a diplomat for about two years and four months, almost all that time at the United Nations.

He said he represented Venezuela on the General Assembly committee dealing with legal issues and was vice chairman for Latin America at last month's first-ever U.N. conference on protecting the world's oceans.

What made him resign?

"The violence and aggressive repression against students" was the final straw, he said.

Medina said it was also "completely incoherent" for Venezuela to be a member of the Geneva-based U.N. Human Rights Council while violating human rights — and to be chairing the U.N.'s decolonization body "while not even allowing the self-determination of its own people."

"The rule of law is so important, and this is why we need to bring the rule of law back," he said.

Medina said he wanted to wait until after the oceans conference, and after he got a passport, to resign.

Getting a passport proved "very difficult," he said, but it was crucial because he didn't want to become stateless when he left his job.

Medina said he signed his resignation and did a video on Thursday and then learned about Ramirez's tweets saying he had been dismissed.

"I respect his opinion but it makes me laugh," Medina said. "How can he fire me after I resign? I guess it's his choice. It doesn't really matter to me."

As for the future, he said he plans to "keep doing what I'm doing."

"I'd like to raise more awareness of the situation in my country," Medina said.

He said he's been an environmentalist for 30 years and is president of a non-governmental organization called wecare2030.org which focuses on the health of the oceans and "changing climate change" — and he will continue that work.

"I resigned my post. I'm free to come and go," Medina said. "Now I have a passport and a (U.S.) tourist visa for 10 years. I've had it for a long time, so I can come in and out."