Two top aides of Venezuelan opposition leader Maria Corina Machado (C) have been arrested in the lead-up to the country's presidential election AFP

Venezuela on Thursday faced a rising tide of international criticism over its arrest of two top aides to opposition leader Maria Corina Machado, a rival to President Nicolas Maduro.

Argentina, Canada, Chile, Colombia, Peru and Uruguay all condemned the latest arrests, declaring them a setback in the run-up to the July 28 presidential election.

UN Secretary-General Antonio Guterres also warned against actions that would interfere with Venezuela's presidential election process, spokesman Farhan Haq said Thursday.

The two aides to Machado, Henry Alviarez and Dignora Hernandez, were arrested Wednesday and have not yet been able to speak with their lawyers, Machado's Vente Venezuela party said on social media platform X.

Chile's foreign ministry said the arrests constituted "an action contrary to the democratic spirit that should prevail in any electoral process."

Argentina said the arrests were a blow to "the emergence of new political leaderships and their legitimization by the citizens."

Venezuelan authorities have linked Machado, 56, who has been disqualified from holding any public office for 15 years, with plans to take "destabilizing actions" ahead of the July 28 vote, including widespread demonstrations and alleged attacks on military installations.

Seven of her party and campaign officials have now been arrested, while another seven are sought by the courts, including Machado's right-hand aide, Magalli Meda, who was considered as an alternative to be nominated in her place.

Though she isn't even on the ballot, Machado is the overwhelming favorite in the race. Some surveys put her support at about 72 percent.

Under the country's electoral rules, her party must decide before Monday who it will register as its candidate.

Haq, the UN spokesman, called for the good faith implementation of an agreement signed last year in Barbados by Maduro's government and the opposition to hold a free and fair vote in 2024 with international observers present.

A Venezuelan Foreign Ministry official rejected the criticisms from abroad.

"It is unacceptable that they stubbornly insist on meddling in the internal affairs of a sovereign country, collaborating with a systematic smear campaign against Venezuela," Vice Minister for Latin America Rander Pena posted on X.

Maduro, a former bus driver and political organizer, is seeking a third term in office amid economic and political crises, and mass emigration.

On Wednesday, Machado said the Venezuelan government was attacking her party for fear of losing the presidential election.

Venezuela's last presidential elections, in 2018, were widely disputed. About 60 countries recognized Maduro's opponent, Juan Guaido, as the winner, although his support ebbed over time.