Venezuelan security forces arrested dozens of people, including two Americans, after a beach invasion allegedly aimed at overthrowing President Nicolas Maduro - a plot said to involve US-backed opposition leader Juan Guaido.

US President Donald Trump on Tuesday said the Venezuela situation "has nothing to do with our government".

"We'll find out. We just heard about it," Trump said when asked about the incident and the Americans' arrest. The Pentagon later on Tuesday echoed Trump's comments.

Maduro held up a pair of blue US passports, reading off the names and birth dates on them in a nationwide broadcast on state television on Monday.

He showed images of the fishing boats the alleged attackers rode in on and equipment such as walkie-talkies and night-vision glasses. He blamed the attacks on the Trump administration and neighbouring Colombia, both of which have denied involvement.

"The United States government is fully and completely involved in this defeated raid," Maduro said, praising members of a fishing village for cornering one group and netting the "professional American mercenaries".

A person familiar with the matter told Reuters news agency the two US citizens were captured on Monday in a second-day round up of accomplices, and were believed to be in the custody of Venezuelan military intelligence. The source, speaking on condition of anonymity, said the details came from contacts with Venezuelan security forces.

A Florida-based ex-Green Beret Jordan Goudreau told The Associated Press he was working with the two American men in a mission launched early on Sunday to "liberate" Venezuela. The operation left eight people dead at a beach near the port city of La Guaira.

He identified the two former US military veterans taken into Venezuelan custody as Luke Denman and Aaron Berry. The two served alongside him in Iraq and Afghanistan, Goudreau said.

Goudreau said the men were part of an mission called Operation Gideon.

Opposition politicians and US authorities issued statements suggesting Maduro's allies fabricated the assault to draw attention away from the country's problems.

Juan Eduardo Romero, a member of the ruling party, told Al Jazeera there is "a war on multiple levels against the government of Maduro".

"The US has decided to keep pushing with a proxy war against a constitutional government. However, the perfect civic-military union that exists in the country remains the best deterrent," he said.

Venezuela has been in a deepening political and economic crisis under Maduro's rule.

Crumbling public services such as running water, electricity and medical care have driven nearly five million people to migrate.

But Maduro still controls all levers of power despite a US-led campaign to remove him. It recently indicted Maduro as a drug trafficker and offered a $15m reward for his arrest.

Venezuela and the US broke diplomatic ties last year amid heightened tensions, so there is no US embassy in Caracas.

"I've tried to engage everybody I know at every level," Goudreau said of the attempt to help his detained colleagues. "Nobody's returning my calls, It's a nightmare."

Goudreau said he signed a contract with the US-backed Venezuelan opposition leader Juan Guaido to overthrow Maduro, which Guaido has denied. The opposition leader said he had nothing to do with Sunday's raid.

Venezuela's attorney general said the contract was valued at $200m and alleged he had seen Guaido's signature on it.

Goudreau said the opposition politician never fulfilled the contract, but he pushed ahead with an underfunded operation with just 60 fighters, including the two US veterans.

He said he last communicated with Denman and Berry when they were adrift in a boat "hugging" the Caribbean coast off Venezuela. They were still in their boat following an initial confrontation with the Venezuelan navy early Sunday, he said.

"They were running dangerously low on fuel," Goudreau said. "If they had gone onto landfall, they would have gone to a safe house."

Goudreau said the two were waiting for a boat on the Caribbean island of Aruba with emergency fuel to help extract them.

Venezuelan authorities said on Monday they arrested another eight "mercenaries" in a coastal town and showed images on state TV of several unidentified men handcuffed and lying prone in a street.

Among them was a National Guardsman Captain Antonio Sequea, who participated in a barracks revolt against Maduro a year ago. Goudreau said Sequea was a commander working with him in recent days on the ground in Venezuela.

Venezuelan state TV showed authorities handling a shirtless Sequea in handcuffs.

Maduro ally and Attorney General Tarek William Saab said in total they arrested 114 people suspected of involvement in the attempted attack and they are on the hunt for 92 others.

Officials in Venezuela's government accuse Colombia and the US of organising and carrying out the attack aiming to overthrow Maduro. Both US and Colombian officials have denied the Venezuelan allegations.

Goudreau, a three-time Bronze Star US combat veteran, said the deadly seaborne raid was launched from Colombia.

An AP investigation published on Friday found Goudreau had been working with a retired Venezuelan army general - who now faces US narcotics charges - to train dozens of deserters from Venezuela's security forces at secret camps inside Colombia.

Guaido on Monday denied having anything to do with the ex-Green Beret. In a statement, he said he has "no relationship nor responsibility for any actions" taken by the US war veteran. (Aljazeera)

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