By Karolos Grohmann

RIO DE JANEIRO (Reuters) - Organizers for the Rio Olympics have delivered on their promises, the International Olympic Committee (IOC) said on Sunday, playing down persistent problems that have plagued the first South American Games since the start.

Games organizers have had to deal with a seemingly endless list of issues affecting venues and infrastructure alike as the country grapples with its worst recession since the 1930s.

From the day of the opening ceremony on Aug. 5, thousands of empty seats have been visible at many venues despite assurances from organizers they would be filled eventually.

Transportation in the traffic-clogged and crime-ridden city has also proved to be a permanent headache while signage around the stadiums and outside venues has been virtually non-existent.

"We still have an issue with look of the Games and signage," said the IOC's Olympic Games Executive Director, Christophe Dubi. "What they have faced is a very unfortunate situation."

According to organizers, contractors failed to deliver the banners on time with only a fraction of them displayed across the city, stadiums and other Olympic areas.

They were equally absent along the route of the women's marathon on Sunday.

"They (banners, signs) could not be delivered on time and they had to change providers. Many things should have been installed and could not," Dubi said.

He did praise organizers for adapting quickly to the situation and at least securing Olympic banners for all fields of play, saying they had also done so when problems arose with the color of the diving pool and other issues.

"Halfway through I think we can say Brazil and the Cariocas (Rio residents) delivered on what they promised," he said. "If we go back in time, they said we would have great venues and we have spectacular venues."

"They said we would have a whole new infrastructure benefiting citizens before the Games and this is what they have done. They said 'we will offer a Carioca experience' and this is what we have. We are were we should be midway through."

He said new sports -- golf and rugby sevens -- had been a success despite initial low attendances and countries such as Singapore, Puerto Rico, Vietnam and Fiji, among others, added their first ever gold medal at these Olympics.

Despite the thumbs-up from the IOC, however, problems will not go away. Organizers are still struggling to clean both pools and get rid of an uninviting green hue for which they blame the contractors.

While managing, after days of delays, to finally turn the synchronized swimming pool back to its blue color, they are not yet able to say the same for the other pool.

"For the diving tank, we could not change it as priority is the competition schedule," said Games spokesman Mario Andrada.

"The water is better than yesterday but we may need another cycle... but I don't think we will need to change the water."

(Reporting by Karolos Grohmann; Editing by Brian Homewood)