Olympics organizers were urgently investigating why several venues had swathes of empty seats on Saturday, the first full day of competition at the London Games.

Organizers LOCOG were overwhelmed with demand for Olympics tickets when they first went on sale more than a year ago.

But there were rows and rows of unoccupied seats at some venues Saturday, notably the Aquatics Center and the Wimbledon tennis complex, causing fans to vent their fury outside venues and on social media.

The embarrassing sight was blamed on accredited bodies, which include the International Olympic Committee, sponsors and the media.

"We are aware that some venues have empty seats," a LOCOG spokesman told AFP. "We believe the empty seats are in accredited seating areas, and we are in the process of finding out who should have been in the seats and why they weren't there."

There were entirely empty blocks at Wembley Arena for the badminton and plenty of unoccupied seats at Greenwich Park for the equestrian events, and at Earls Court for the volleyball.

Britain's Olympics minister Jeremy Hunt called the situation a "shame" and "very disappointing".

One angry punter at the Olympic Park told BBC television he blamed corporate ticket-holders.

"It's not fair. There's thousands of people who would have got into that swimming pool to watch the races this morning and couldn't get in.

"They've (now) panicked about the political situation of the stadium being empty. We couldn't even get in but people were coming out saying how the stadium was half-empty.

"There were thousands of people stood outside wishing to go in."

During the Wimbledon championships, a match between British hopeful Anne Keothavong and former world number one Caroline Wozniacki on the 15,000-seater Center Court would normally be played before a packed house.

But Center Court was half-empty for the match on Saturday.

"Very surprised at amount of empty seats on Wimbledon Center Court, especially as I applied for some! It can't be more than 50 percent full," wrote frustrated fan Alex Dover on Twitter.

"We're looking at this very urgently," Olympics minister Hunt told the BBC. "We want to make sure this kind of thing doesn't happen."

If sponsors are not going to turn up and take their seats, "we want those tickets to be available for members of the public," he said.

"It's a shame this happened but we're going to do everything to make sure that we fill up those stadia."

[image via Agence France-Presse]