Many other nations missed the Championships and Agapitov, who sits on the Executive Board of the IWF, said the event was "a failure".

Mohamed Jaloud, general secretary of the IWF, was among others who criticised the US for "disrespectful" delays in issuing visas.

The host federation, USA Weightlifting (USAW), said it had sent notifications about visa deadlines eight times since last July, had offered to pay travel expenses for Russia's team to obtain visas and that late applications from member federations had been a "major and consistent problem".

"USA Weightlifting and the US Olympic Committee have supported all requests from national federations for support in visa applications," said Phil Andrews, chief executive of USAW.

Andrews did acknowledge, though, that there had been problems with visas.

"USA Weightlifting has received feedback that some federations have reported that it has been more challenging to procure visas for this Championship than in 2015 or 2017 IWF World Championship events hosted by the USA or the 2013, 2014 or 2017 Pan American events hosted in the USA," Andrews said.

There were visa problems before the IWF World Championships in Anaheim in 2017.

Iran's lifters, and especially the Olympic champion Kianoush Rostami, were unsure whether they would be able to compete until a few days before those Championships because no visas were issued in Iran.

This year's Youth World Championships were attended by 42 nations, about 22 per cent of the IWF's total membership and a significant drop on numbers from the 2017 event in Thailand, where more than 50 took part.

The number of athletes who competed in Las Vegas, where the host nation finished top of both the men's and women's medals tables for the first time, was 175.

"There are usually more registered entrants at Russian Youth Championships, not mentioning tournaments in Europe, where the number of registered participants exceeds the number of weightlifters taking part [in Las Vegas]," Agapitov told TASS, the Russian news agency.

"A number of top national teams did not come to the United States for the Championships and among them were China, North Korea, Iran, Venezuela, Belarus, Ukraine, as well as many leading weightlifters from other national teams.

"However, despite the extremely low number of participants, the Americans and the head of the IWF keep denying the fact that the tournament in Las Vegas was a failure and its results are dubious.

"On top of all, the American weightlifting federation keeps declaring that weightlifters of all national federations were granted American visas."

Agapitov said his federation began the application process for visas in good time but "it turned out to be impossible to receive visas".

Alexander Kishkjin, director general of the RWF, explained that Russians could only apply for visas at embassies outside Russia, because of conditions imposed by the US State Department.

He said that the inability of young weightlifters to travel abroad without being accompanied by legally authorised guardians only complicated that process.

Kishkin said the Russian team's coaching staff also objected to the teenagers having to leave the country for visas as the process would take time and would disrupt their training programme.

Early in the year, Kishkin told TASS his federation had tried submitting visa applications at the US Embassy in Moscow, but was told interviews were mandatory, and the earliest available interview dates were after the Youth World Championships had finished.

Andrews disputed some of these comments, pointing out that the reduced visa operations in Moscow were a result of Russian Government sanctions, that a parent or guardian did not have to be present at athletes' visa interviews and that the Russians applied too late.

Having been advised, along with all other nations, to apply by December 1, 2018, the RWF did not provide an intent to apply for visas until January 4, said Andrews.

"This date is considered significantly late as it is within 90 days of the start of the competition," he said.

"Despite this late notification, both USA Weightlifting and the United States Olympic Committee supported it by providing a list of appointment wait times at nearby locations in third countries, with the recommendation of Riga, Latvia or Minsk, Belarus since both had wait times of one to three days.

"USA Weightlifting further offered to assist with the cost of the team's travel to the interview.

"This offer was made to the Russian Weightlifting Federation President on February 7, and repeated on February 13, 18 and 20.

"It should be noted Russian teams from other sports have successfully obtained visas through these same procedures to facilitate their participation, with no assistance."

Andrews did acknowledge that visa problems had been partly responsible for the decision of Iran not to send a team.

There was no explanation for China or North Korea's decision not to compete.

Syria applied very late but the team was issued with visas and did compete.

Agapitov told TASS that Yousef Al Mana, President of the Asian Weightlifting Federation, had written to the IWF President, Tamás Aján, to express his concern over the low turnout in Las Vegas "and urged the global federation to draw relevant conclusions". 

Jaloud, who is based in Kazakhstan and constantly travels the world in his role as IWF general secretary, did not receive a visa until the days before the event started.

"It is always the same, they always want to know why did you go here, why were you in North Korea, what were you in this country for," he said.

"Of course I have to go there - it is my job as general secretary of the IWF.

"I feel it is disrespectful to somebody who works for an international sports federation."

Andrews said: "Mr Jaloud required administrative processing.

"Due to confidentiality policies, we are not able to inquire further about the details of his administrative processing.

"On the last night of the event Mr Jaloud noted it had been very successful and that the visa issue had been resolved."