Earlier this month the EU temporarily removed individual sanctions on Amoroso, a move which he rejected, saying all sanctions on Venezuela should be lifted.

Shortly afterward, the government-controlled legislature approved a measure to ask the CNE to revoke the invitation for EU electoral observers.

"They are not worthy people to come to this country ... while they maintain sanctions," Amoroso said while reading a statement on state television.

EU sanctions are colonialist and "coercive, unilateral and genocidal," Amoroso said in the statement.

The EU office in Caracas said in a statement later on Tuesday it "deeply regrets" the CNE's decision and called for the body to reconsider it, saying elections should take place transparently and supported by international observation.

The Community of Latin American and Caribbean States (CELAC), the Caribbean Community (CARICOM), a panel of experts from the United Nations, the African Union and the Carter Center, among others, will attend as observers, Amoroso added.

The July vote is the first time in a decade the opposition, which boycotted the 2018 election, is participating in a presidential contest.

President Nicolas Maduro of the Socialist ruling party is seeking his third term, while former diplomat Edmundo Gonzalez has thrown his hat in the ring on behalf of a major opposition coalition.

Maduro's government reached a deal with the opposition last year to hold elections, prompting the United States to temporarily ease oil sanctions.

Washington then re-imposed sanctions on the oil industry in April, saying the government had not done enough to make the electoral process fair.

The opposition has heavily criticized the government's handling of the election, especially after the winner of its primary, Maria Corina Machado, had a public office ban upheld by the country's top court, forcing the selection of Gonzalez as a replacement.

A recent survey showed 50% of voters backing Gonzalez, with 32% favoring Maduro. The poll had a margin of error of 3.16%.