BUENOS AIRES (Reuters) - Some Venezuelan opposition leaders have sought refuge at the Argentine embassy in Caracas, the Argentine government said in a statement late on Tuesday, adding that it was concerned over what it called a deterioration of institutions and persecution towards those opposed to President Nicolas Maduro.

Argentina's foreign ministry declined to disclose the names of the Venezuelan politicians that it said were at its embassy, citing security reasons.

Local media reported they were six politicians linked to Maria Corina Machado, an opposition leader who was barred from registering for July's presidential election despite winning an opposition primary.

The Argentine government expressed its "concern over the deterioration of institutions and the acts of harassment and persecution directed against political figures in Venezuela," the statement said.

Venezuela's government did not immediately reply to a request for comment.

A major Venezuelan opposition group registered Edmundo Gonzalez, a former ambassador, for the presidential election on Tuesday to ensure a spot on the ballot, following Machado's ban and the inability of her replacement, Corina Yoris, to sign up on the online registration system.

Last week, Venezuela's attorney general Tarek Saab said two people close to Machado had been arrested. Seven other members of her team, including her right-hand Magalli Meda, have warrants out for their detention.

Argentina, which has not had a designated ambassador in Venezuela since right-wing President Javier Milei took office in December, also expressed its concern about a power outage at its residence in Caracas.

(Reporting by Lucila Sigal in Buenos Aires; Additional reporting by Vivian Sequera in Caracas; Writing by Valentine Hilaire; Editing by Rosalba O'Brien)