In Venezuela, another blow to the opposition's efforts to oust President Nicolas Maduro from office. The country's electoral authority has blocked plans for a recall referendum. The opposition says it's not giving up and will continue the nationwide protests.

"Recall referendum now", chanted this group of students in Caracas on Friday morning,

That is looking increasingly unlikely, as the Venezuelan government shows its determination to stop, or at least stall, the process.

The latest setback involves a legal challenge to the initial petition calling for a referendum, which the opposition organized last April.

Nine times the number of required signatures were gathered. Venezuela's pro-government electoral authority eventually declared that enough were valid and the recall process could proceed.

But on Thursday, several regional courts declared the petition was suspicious.

Government supporters - via lurid videos like this one - claim that the names of thousands of deceased voters have shown up on the forms.

That doubt - dismissed as baseless by the opposition - has been enough for the electoral authority to call off the second stage of the vote.

The government was quick to express its pleasure.

"We salute the fact that justice is beginning to be done to compensate the thousands of victims of this huge fraud," said Jorge Rodriguez, Signature Verification Commission.

Venezuela's opposition says this is all tantamount to an attack on the country's constitution, by the government itself.

"And so we are announcing to all the Venezuelan people that the time has come to defend the Constitution of the Bolivarian Republic of Venezuela," said Henrique Capriles, Venezuelan opposition leader.

And on the streets of Caracas many agree. But some are with the government.

The target of the recall process - Nicolas Maduro - is not currently in the country.

He is visiting oil-producing countries hoping to stabilize the oil price - the fall of which has played an important part in his declining popularity.