The observers reported polls saw better conditions than previous years, but raised concerns over some practices.
Venezuelan President Nicolas Maduro has dismissed as â€œspiesâ€ members of a European Union electoral observation mission sent to observe last weekâ€™s regional polls.
The condemnation from Maduro came on Sunday after the observers said the polls, in which opposition candidates participated for the first time in four years, were generally better conducted than previous years.
However, they raised concerns over arbitrary bans on candidates for administrative reasons, delays in opening voting centres and â€œextended use of state resources in the campaignâ€.
Maduro, whose governing Socialist Party largely swept the gubernatorial and mayoral elections, said the EU observers sought to â€œstain the electoral process and they couldnâ€™tâ€.
â€œA delegation of spies â€“ they werenâ€™t observers â€“ wandered freely around the country, spying on the countryâ€™s social, economic and political life,â€ Maduro said during a broadcast on state television, adding that the elections were â€œimpeccable, beautifulâ€.
The observer mission did not immediately respond to the claims.
The EU observers deployed to the country for the first time in 15 years as part of several concessions from Maduroâ€™s government to encourage the participation of opposition candidates, who have boycotted all elections in the country since 2018 amid allegations of fraud and intimidation.
The concessions came amid a wider push by Maduro, who was first elected president in 2013, to curry favour with Western powers in hopes of relief from sanctions, which have crippled the countryâ€™s already flailing economy.
The US is among dozens of countries that have not recognised Maduroâ€™s presidency since the controversial 2018 national elections, which opposition leader Juan Guaido claimed to have won.
The 1,000-member EU team will present a full report on the elections in two months.
Opposition candidates saw little success in the most recent elections, picking up just three of 23 governorships and 117 mayoral positions to the governing partyâ€™s 210 mayoral victories.
Several mayoral races had yet to be called, and one governorâ€™s office â€“ in the heavily Maduro-leaning Barinas state â€“ has also not been called.
Despite the victories, votes for the Socialists dwindled to fewer than four million, according to figures from the countryâ€™s electoral authority, down from the 5.9 million it won during regional elections in 2017.
On Sunday, Maduro also said he will hold meetings in â€œthe coming hoursâ€ with opposition governors, but did not offer details.