The Pink Floyd co-founder Roger Waters has criticised an upcoming Live Aid-style concert to raise funds for humanitarian aid for Venezuela, by claiming it is a US-backed effort to tarnish the socialist government.

The billionaire Richard Branson has backed the Friday show in the Colombian border city of Cúcuta with a fundraising target of $100m (£77m) to provide food and medicine for Venezuelans suffering widespread shortages.

The row came as Venezuelan security forces were accused of executing dozens of people and arbitrarily detaining hundreds of others in a campaign to punish people who protested against President Nicolas Maduro. Amnesty International said in a report that 41 people had died, mostly from gunshot wounds, in five days of protests in late January. It said it had documented six extrajudicial executions by the National Police’s Special Actions Force (FAES) of young men linked to the protests.

The Latin singers Alejandro Sanz, Nacho, Luis Fonsi and Maluma have so far confirmed they will perform in the concert, which has evoked comparisons to the Irish rock star Bob Geldof’s 1985 global Live Aid concert to raise money for famine relief in Ethiopia.

“It has nothing to do with humanitarian aid at all,” Waters said. “It has to do with Richard Branson … having bought the US saying, ‘We have decided to take over Venezuela, for whatever our reasons may be.’”

Venezuela Aid Live is part of a broader western relief effort organised by Venezuela’s opposition, which has blamed the ruling Socialist party for rampant hyperinflation and the economy’s subsequent downwards spiral that has sparked the exodus of millions.

President Maduro, who is facing growing international pressure to step down after his disputed re-election last year, denies there is a humanitarian crisis.

“Richard is helping them to raise awareness of the crisis in Venezuela and raise much-needed funds through this event,” a spokesperson for Virgin, which handles media inquiries for Branson, said in a statement. “This is not a political statement and the US is not involved in any aspect of this.”

Donald Trump’s administration has openly backed Maduro’s rival and Venezuela’s congress chief, Juan Guaidó, who in January invoked constitutional provisions to declare himself interim president.

The opposition plans to bring aid into Venezuela on Saturday from collection points in neighbouring countries including Cúcuta via sea and land, despite Maduro’s refusal to let it in, setting up a possible clash with authorities.

Waters, the British rock group’s principal songwriter, said the relief effort was part of the attempts by the US to paint a false picture of Venezuela to justify regime change.

He said there was “no mayhem, no murder, no apparent dictatorship” in Venezuela, despite even government data putting the homicide rate among the world’s highest. Waters added: “Do we really want Venezuela to turn in to another Iraq or Syria or Libya? I don’t and neither do the Venezuelan people.”

This is not the first time that the musician has commented on South American politics. During a concert in Brazil ahead of presidential elections there last year, Waters spoke out against the rightwing candidate Jair Bolsonaro, who is now president.

Maduro’s government this week announced two concerts on Friday and Saturday just across the border from Cúcuta to rival Branson’s Aid Live show.