The family of a US man detained in the Democratic Republic of Congo says they have "zero idea" how he became entangled in an abortive coup attempt last month.

Utah resident Tyler Thompson, 21, was travelling outside the US for the first time with his friend Marcel Malanga, whose father reportedly led the attempted coup.

Fifty suspects, including three Americans, were detained after the 19 May incident, which saw dozens of heavily armed men occupy the Palais de la Nation, the office of the DR Congo's president.

Mr Thompson's family have not heard anything about him since and US consular officials have not been allowed to see him.

The BBC has contacted the Congolese army and information ministry for comment.

The attempted coup was reportedly organised by Christian Malanga, a formerly exiled DR Congo politician who was shot dead by Congolese forces in the country's capital Kinshasa, reportedly after resisting arrest.

Six people were killed during the attacks on the presidential palace and the home of a close ally of DR Congo President Félix Tshisekedi.

Videos taken in Kinshasa after the incident show Mr Thompson being hit with the butt of a rifle and repeatedly struck in the head by Congolese security forces.

In an interview with the BBC, his stepmother Miranda Thompson said that the family was in a state of disbelief after learning that Mr Thompson was detained.

"We have zero idea how he ended up there," she said.

"We were in complete shock as to what was happening, and the unknown. Everything we were learning was what we were getting off Google."

Mrs Thompson said that the family is unsure how Mr Thompson - who works at a construction firm in Utah - found himself in the middle of the failed coup.

She said he had been invited to travel with the Malanga family to DR Congo by Marcel, who was born in the US and is a US citizen.

"They were going to explore and see a part of the world that Tyler never expected to see," she said.

"When the opportunity came up - why not?"

A friend of Mr Thompson and the younger Mr Malanga, Daniel Gonzalez, told the Associated Press that he had been offered between $50,000 (£39,175) and $100,000 to serve as a security guard for the elder Mr Malanga.

The Thompson family says they were unaware of that.

The US State Department and the Thompson family say that consular officials have still not been granted access to see him.

"We don't know anything about his current condition," Mrs Thompson said.

"We're concerned for his health. We saw him get hit in the head, multiple times."

In a statement to the BBC, a spokesperson for the State Department said it has requested consular access to "any" US citizens detained after the coup, but "have not received it to date".

The family has launched a campaign to encourage people in Utah and elsewhere in the US to send letters to officials urging them to pressure Washington to do more to secure Mr Thompson's release.

The family has also been in contact with Utah lawmakers.

"We're trying to get the government to push as hard as they can," Mrs Thompson said.

"If public pressure helps make that happen, that's what we'll give them."

Mrs Thompson - who described her stepson as "incredibly kind and generous" - said that they are sure the coup attempt "wasn't something he would choose" to participate in.

"He's definitely not a politically active kid," she said.

"He's not someone who is going to go in and make this choice...he's just a kid who was in the wrong place at the wrong time."

Asked what message she would send to authorities in DR Congo, Mrs Thompson said the family simply "wants to know that he's OK and healthy".

"We know that getting him home is going to be a process...but without access to him, we don't know any of those things," she added.

"Any parent would want that."