Security forces in Venezuela have fired tear gas and rubber bullets at people protesting Sunday’s disputed election result.
Thousands of people descended on central Caracas on Monday evening, some walking for miles from slums on the mountains surrounding the city, towards the presidential palace.
Protests erupted in the Venezuelan capital the day after President Nicolás Maduro claimed victory.
The opposition has disputed Mr Maduro`s declaration as fraudulent, saying its candidate Edmundo González won convincingly with 73.2% of the vote.
Venezuela`s security forces clashed with large crowds of protesters who took to the streets to denounce the re-election of President Maduro as fraudulent
Opinion polls ahead of the election suggested a clear victory for the challenger.
Opposition parties had united behind Mr González in an attempt to unseat President Maduro after 11 years in power, amid widespread discontent over the country`s economic crisis.
A heavy military and police presence was on the streets of Caracas with the aim of trying to disperse protesters and prevent them from approaching the presidential palace.
Crowds of people chanted “freedom, freedom!” and called for the government to fall.
Footage showed tyres burning on highways and large numbers of people on the streets, with police on motorbikes firing tear gas.
In some areas, posters of President Maduro were ripped down and burned while tyres, cars and rubbish were also set alight.
Armed police, military and left-wing paramilitaries who are sympathetic to the government clashed with protesters and blocked off many roads around the city centre.
Venezuela`s government also announced a temporary suspension of commercial air flights to and from Venezuela with Panama and the Dominican Republic starting from 20:00 local time on Wednesday.
In a speech on Venezuelan state television, Mr Maduro said it is his "obligation to tell you the truth".
"We are all under the obligation to listen the truth, to gear up with patience, calmness and strength because we are familiar with this movie and we know how to face these situations and how to defeat the violent.”
The BBC spoke to a number of people who attended one protest in a densely-populated area known as La Lucha, meaning “the fight”.
Paola Sarzalejo, 41, said the vote was “terrible, fraud. We won with 70%, but they did the same thing to us again. They took the elections from us again.
“We want a better future for our youth, for our country."
Her father Miguel, 64, agreed, saying: “He lost the elections, he has no right to be there right now.”
He added: “We want a better future for the youth because if not they will leave the country. One where they can work well and earn well. We have a rich country and he is destroying everything.
“If the youth all leave, only old people will be left in Venezuela, only senior citizens.”
The Sarzalejos (C) are concerned that most young people will leave Venezuela because of Mr Maduro
Cristobal Martinez, draped in a Venezuelan flag, said he thought the election was a “fraud”.
He said most young people in La Lucha and surrounding areas had voted in an election that was particularly important for young people as “many of us are unemployed” and “the majority do not study”.
"It was the first time I have voted in my life. I was there from six in the morning until approximately nine in the morning and I saw a lot of people mobilising in the street.
"There was a lot of discontent towards the government. The majority of people were participating for change.”
He said while President Maduro had been in office for a long time there had not been “any change” and it had been “worse since President Chavez died”.
He accused some older people who sympathised with the government of living off bonuses or food handouts whereas “we want a change, we want decent jobs, a good future for our country”.
Mr Martinez said he wanted “people from other countries to help us... so that a disaster doesn’t happen like in previous times”.
Cristobal Martinez said people wanted jobs and a future
Mr Maduro has accused the opposition of calling for a coup by disputing the results. "This is not the first time we are facing what we are facing today,” he said.
“They are trying to impose in Venezuela a coup d`etat again of fascist and counter-revolutionary character."
The Venezuelan attorney general warned that the blocking of roads or breaking any laws related to disturbances as part of protests would be met with the full force of the law.
He said 32 people had been detained on accusations ranging from destroying electoral materials to sparking acts of violence.
A number of Western and Latin American countries, as well as international bodies including the UN, have called on the Venezuelan authorities to release voting records from individual polling stations.
Argentina is one country which has refused to recognise President Maduro`s election victory, and in response Venezuela recalled diplomats from Buenos Aires.
Diplomats from six other Latin American countries - Chile, Costa Rica, Panama, Peru, the Dominican Republic and Uruguay - have also been withdrawn for what Foreign Affairs Minister Yvan Gil described on social media as "interventionist actions and statements".
Meanwhile, US senior administration officials said that the announced result “does not track with data that we`ve received through quick count mechanisms and other sources, which suggests that the result that was announced may be at odds with how people voted”.
That was “the principal source of our concern”, they added.
“That is why we are asking the Venezuelan electoral authorities to release the underlying data that supports the numbers that they have publicly announced.”
However, the US has not yet been drawn on what the result means for their sanctions policy towards Venezuela. Officials have emphasised that while they have doubts about the result, President Maduro did call an election and allow an opposition candidate to be on the ballot paper - even if the opposition leader was banned from running.
The Organization of American States (OAS) announced late on Monday it will hold a meeting on Wednesday of its permanent council over the Venezuelan results.