[CARACAS] Riot cops fired tear gas to head off a protest march Wednesday by opponents of Venezuela's President Nicolas Maduro who were demanding a referendum on removing him from office.
Political leaders and analysts warned tensions could erupt into unrest as the centre-right opposition staged rallies across the crisis-hit South American country.
Protesters were demanding electoral authorities quickly approve their call for a vote on dumping the socialist leader.
Security forces blocked the street to keep demonstrators away from the headquarters of the National Electoral Board (CNE) in Caracas. A small number of tear gas canisters were fired.
The opposition coalition MUD said in a statement that one of its top leaders, Henrique Capriles, was affected by the tear gas as he led the march.
"I am alright. We Venezuelans want a recall referendum and change," Mr Capriles wrote later on Twitter.
"Maduro will not overcome the people!"
The Democratic Unity Roundtable (MUD) blames Mr Maduro for an economic crisis in which Venezuelans are having to queue for hours for rations of basic food and other goods.
Mr Maduro has also imposed daily electricity blackouts and has public employees working just two days a week due to power shortages.
Security forces reportedly blocked streets to head off similar demonstrations Wednesday in other towns such as Zulia in the northeast.
Separately, looting reportedly broke out at a food store in the city of Maracay, state ombudsman Tarek William Saab told reporters.
With robberies and violence reportedly surging, the military also said Tuesday that nine people had been killed in a crackdown by security forces around Caracas.
Some 3,000 troops and police have been deployed there to go after gangs, the government said.
Thousands of supporters of Mr Maduro also rallied separately on Wednesday in the centre of the capital.
The Democratic Unity Roundtable a week ago handed in 1.8 million signatures petitioning for a referendum.
Under electoral rules, the CNE was supposed to count those signatures by last Monday and then authenticate them within five days before authorizing the opposition to seek a further four million signatures to call a referendum.
Venezuela has the biggest oil reserves in the world but its revenues have plunged in line with the price of crude over the past two years, starving the country of dollars to import goods.
Mr Maduro blames the crisis on a plot by capitalists and accuses the opposition of trying to mount a coup against him.
"They will not get rid of me by one way or another," he said on Tuesday.
Opposition leaders have until the end of this year to hold the referendum if they want new elections. But there are several procedural steps to go through with the CNE.
The opposition accuses the government of controlling the board and seeking to delay the process.
Under Venezuela's constitution, after January 2017 a successful recall vote would transfer power to Mr Maduro's vice president rather than trigger new elections.
Anti-government protests in 2014 led to clashes that left 43 people dead.
"We do not want to show the least bit of violence. This is a march for peace," said the MUD leader in parliament, Julio Borges, on Wednesday.
"The government is so cowardly that it is afraid of the people. It will not let us advance".
Analysts warn the situation could become increasingly volatile.
"The government effort to block the recall referendum is likely to gradually increase the risks of destabilizing protests," said Diego Moya-Ocampos, an analyst at research group IHS.
"While protests are likely to start peacefully, they would become violent if security forces prevent protestors from reaching the CNE or if they or pro-government groups confront protestors."