CARACAS —Corina Yoris was nominated as the PUD's candidate on Friday but has been unable to register

Venezuela's main opposition coalition says its candidate has been blocked from July's presidential election.

The opposition Unitary Platform (PUD) said it was unable to access the electoral council website to register its candidate, Corina Yoris.

It is the latest setback for the PUD, whose leader, María Corina Machado, has been barred from running for office.

Polls have suggested that if the election was free and fair, Machado could beat President Nicolás Maduro.

Ms Machado, 56, made headlines in October when the notoriously divided opposition united behind her. She received more than 90% of votes in a primary election organized by the opposition.

The primary was denounced by the government of President Maduro as illegitimate and Machado and members of her Vente Venezuela party have been targeted by the authorities since her overwhelming win.

Several regional campaign officials have been jailed over the past months.

And only last week, arrest warrants were issued for her campaign manager and eight other staffers, who have been accused of taking part in a conspiracy to overthrow President Maduro.

María Corina Machado herself had a ban which prevents her from running for public office confirmed by the Supreme Court, which is stacked with government loyalists.

President Maduro, who has been in power since 2013, has withstood international pressure to allow Machado to run in the presidential election scheduled for 28 July.

He told his supporters last month that "we're going to win by hook or by crook, we're going to win, always".

With the deadline for the registration of candidates fast approaching and Machado's ban still in place, the PUD on Friday picked Corina Yoris to replace her.

Yoris, an 80-year-old academic, is relatively unknown even in opposition circles. The fact that she is a newcomer to politics was seen as an asset by the coalition, which argued that this made it harder for her opponents to discredit her.

Even so, she has already had to rebut allegations that she was born outside of Venezuela, which would have made her ineligible for the presidency.

When it came to registering her candidacy by the deadline set for Monday evening, however, the opposition coalition hit a wall.

In videos uploaded to social media, the PUD showed how they repeatedly tried and failed to log into the electoral council website to register Yoris's candidacy.

Yoris said that her rights as a Venezuelan citizen had been "violated" by being blocked from registering.

She also said that when her team was faced with the unresponsive website, they had visited the electoral council in person to ask for an extension to the deadline, which was not granted.

After the midnight deadline had passed, PUD official Omar Barboza said in a video statement: "We have been working all day (...) trying to exercise our constitutional right to nominate our candidate. This was not possible."

President Maduro, meanwhile, had no problems registering his candidacy for a third consecutive term in office.

Thousands of people dressed in the red color associated with his socialist PSUV party cheered him at a rally outside the electoral council office.

He told them that "today, I have not just come to register (...) but to invite you to keep dreaming and continue transforming our reality, taking it forward to the future".

Nine other people from a variety of small parties were also able to register their candidacy —some are aligned with the government and none of them is thought to be a serious challenger to President Maduro. — BBC