Venezuela's ambassador to the UN says he is resigning his post in protest at President Hugo Chavez's policies.
Venezuela has been shaken by several days of protests
Milos Alcalay told a news conference in New York that he had always worked to promote democracy, human rights and a non-confrontational foreign policy.
"Sadly, Venezuela now is operating devoid of these fundamental principles," Mr Alcalay said.
As further anti-Chavez protests took place across the country a local opposition leader was killed.
Democratic Action party leader Eva Carrizo was killed when protestors backing a recall referendum clashed with National Guard troops in Zulia state, 600 kilometres (375 miles) west of Caracas.
Carrizo was shot dead as the demonstration in the city of Machique turned violent, according to regional lawmaker Elias Mata.
Eight people have now been killed and dozens injured in unrest since last Friday.
Venezuela has seen increasing tension over opposition attempts to force a referendum on Mr Chavez's rule.
Opponents of Mr Chavez have been protesting against an announcement by the electoral authorities that they had not gathered enough signatures, so far, to call a referendum on his future.
Marchers call for the release of people arrested during the protests
The electoral authorities ruled on Tuesday that not enough valid signatures had been collected in a petition to force such a vote.
The opposition is currently negotiating with the government and electoral officials over ways of checking over one million signatures deemed in need of further verification.
Mr Alcalay said the actions of the National Electoral Council - which says some 1.1 million signatures need further verification - "rob Venezuelans of the right to effect change through the democratic process".
He said Venezuela was seeing army and police repression, unacceptable loss of life and that peaceful protest were no longer possible.
Mr Alcalay, a career diplomat for 30 years, warned that "the increasing bipolarisation and problems we are experiencing at home in Venezuela have impacted on our relationships around the world."
But the ambassador said that if Mr Chavez showed his respect for the rules of government, human rights and democracy, he could work with him.
The government's response was swift, insisting that democracy and human rights were respected in Venezuela, before calling into question Mr Alcalay's role in the short-lived coup that briefly ousted Mr Chavez in April 2002.
Venezuela is deeply divided over President Chavez, with his supporters regarding him as a champion of the poor and his opponents viewing him as dangerously autocratic.
On Thursday, several hundred people marched through Caracas calling for the release of more than 300 people they say were arrested during the recent protests.
They held up pictures of an opposition politician, Carlos Melo, detained on charges of weapons possession.
At the same time, pro-Chavez supporters held a demonstration urging people to make sure their names were not fraudulently included on the opposition's petition.