Venezuela’s opposition has vowed to turn up the pressure on the socialist government of President Nicolás Maduro, calling for a national strike on Friday and a march on the presidential palace next week to demand a recall referendum against the troubled leader.

“Either the government restores the constitution, or on 3 November we march to the palace,” Henrique Capriles, a former presidential candidate and opposition leader, said before hundreds of thousands of protesters at a march in Caracas on Wednesday.

Crowds chanted, many wearing white and waving national flags, chanted: “This government is going to fall!” as they congregated at nearly 50 sites across the country.

Capriles blamed authorities for injuring more than 120 people and detaining 147 protesters.

Clashes occurred in several cities outside Caracas, witnesses said, including the Andean city of Merida and the volatile western town of San Cristobal that was an epicenter of violence during 2014 anti-Maduro protests.

Opposition activists and student leaders said there were at least five protesters reportedly struck by bullets in Venezuela’s second-largest city Maracaibo and San Cristobal.

Local media later reported a policeman had been shot in a protest on the outskirts of Caracas. The Miranda state police force confirmed the death, but said the officer and his colleagues had been attacked and did not link the incident to the opposition protest.

Critics say the government has disregarded the constitution by preventing a recall referendum against Maduro, who faces low approval ratings, high crime rates and food scarcity that is leaving many Venezuelans hungry.

“I came because we can’t take this situation any longer. I don’t want us to be humiliated any more,” said marcher Marisela Flores, a resident of El Hatillo, one of the five municipalities that make up Caracas.

Electoral officials closed the door on a recall process last week after five lower courts found that fraud had been involved in a petition to trigger the referendum. “Putting the brakes on the recall, which was our only electoral and peaceful way out, is the last straw,” she said.

Maduro called for a national dialogue to ease tensions but the opposition is wary of any attempt at negotiation. “I call the Venezuelan people to a political and social dialogue for the prosperity of Venezuela,” Maduro said. “Venezuela should close the chapter of political violence.”

Vatican-brokered talks between the government and opposition are reportedly scheduled for Sunday on the island of Margarita. However some sectors of the opposition coalition, known as MUD, have said they would participate only if the talks are held in Caracas.

Meanwhile Maduro held a meeting of the national defence council, to address the economic and security crises of the country. Venezuela is home to the world’s largest oil reserves but falling oil prices coupled with years of price and currency controls have led to severe shortages of food and medicine.

Henry Ramos Allup, the speaker of the assembly, was invited to attend the council meeting but refused. “I will not take part in that piece of theatre,” he said. “I will not play the part of the fool.”

However Maduro said that the national assembly – controlled by the opposition after a landslide victory in elections last December – had become irrelevant. “I think the national assembly’s time is up,” he said, in a televised address from Miraflores, the presidential palace.

On Tuesday the assembly voted to begin a political trial against Maduro, although it is largely symbolic as impeachment does not exist in Venezuela. Henry Ramos Allup, president of the assembly, told supporters that lawmakers would declare that Maduro has “abandoned his responsibilities”.

The assembly summoned the president to appear in the legislature on 1 November but Maduro was unlikely to attend, calling the attempt to put him on trial a “parliamentary coup”.

Although some protesters on Wednesday wanted to march on the Miraflores palace at once to show their anger at the seat of the presidency, the marchers remained on the mostly anti-government eastern sectors of the city.

Holding off until next week to go to Miraflores “gives the government more oxygen,” said Douglas Monzón, a resident of a working class suburb of Caracas called the Valles del Tuy.

After speaking to the crowd, Capriles called on marchers to go home peacefully.

In 2002 a massive protest march against the then president, Hugo Chávez, that reached the presidential palace led to deadly violence between pro and anti-government demonstrators and a brief coup d’état against the charismatic firebrand, who was restored to power two days later.

Yaneis Torrealba, also a resident of Valles del Tuy and a fervent supporter of Chávez, said the socialism he tried to create in the oil-flushed country failed in 2013. “It died when Chávez died,” she said. She too would have liked to have marched all the way to Miraflores on Wednesday. “Today is when we should all stay on the streets,” Torrealba said.