LONDON – Hoping to quell controversy after large swaths of seats appeared unfilled, London Olympic organizers said British troops and schoolchildren had been given free tickets Sunday to fill many of the vacant rows.

A day after the city reveled in the splendor of Danny Boyle’s critically acclaimed opening ceremonies, many locals were piqued Saturday when television footage showed empty seats at some of the most popular sporting events, including swimming and gymnastics, that they had been told were sold out. Such scenes ignited speculation that corporate sponsors had been provided tickets they weren’t using, leaving the public on the outside looking in.

Culture Secretary Jeremy Hunt, the minister responsible for the Olympics, said the organizing committee was “doing a full investigation into what happened. … We think it was accredited seats that belong to sponsors, but if they are not going to turn up, we want those tickets to be available for members of the public, because that creates the best atmosphere.”

The International Olympic Committee moved quickly to quash those rumors, saying sponsors had been allocated about 8 percent of available tickets, while at the same time they tried to determine exactly whom the unused seats belonged to.

At a briefing at the Olympic Park, IOC Communications Director Mark Adams said blame for the no-shows was widespread.

“There are a range of people, four or five different groups,” Adams said, “ranging, as you heard, from the federations, the actual sports organizations involved, athletes as well, some media tickets there as well, by the way, and actually I would say it is about a handful of sponsors.”

Several sponsors, including Coca-Cola, Visa and McDonald’s, issued statements Sunday denying they had failed to use their allocated tickets.

Ticketing has been a particularly touchy issue. Hundreds of thousands failed to secure seats for the events they wanted after a complicated lottery process.

Officials said they have sold more than 7 million tickets – more than were sold at the Beijing Games in 2008 – and unticketed events such as the 155-mile men’s cycling road race Saturday attracted more than 1 million spectators who lined a route stretching from outside of Buckingham Palace to the English countryside.

On Sunday, many venues appeared full, but there were reports of empty seats at the Basketball Arena and Greenwich Park, where Zara Phillips, the queen’s granddaughter, was competing in equestrian events.

London 2012 chairman Sebastian Coe said off-duty military and students already accredited for the Olympic Park would be offered the abandoned seats. British troops already were attending women’s gymnastics Sunday morning, Coe said.

Coe also insisted the the issue would disappear after the preliminary rounds when interest would grow.