Rio de Janeiro, (IANS): The organisers of the 2016 Rio Olympics are facing a tricky issue of the water pollution, a media report said.

The issue that has most attracted the world's attention so far is the cleanup work at Guanabara bay, that will host Olympic sailing, and the Rodrigo de Freitas lake, home to rowing and canoeing, Xinhua reported on Wednesday.

The press conferences held by the Rio Organizing Committee were always dominated by questions about Rio's sewage pollution problem.

Media reports have claimed that both venues remain littered with rubbish and sewage, prompting concerns from health experts about possible risks to athletes.

Recently an independent analysis of water quality also showed high level of viruses and bacteria from the sewage in all Olympic water venues.

In order to fully test the venue, a second sailing test event was held last week.

Throughout the event, there have been worries about the levels of bacteria and viruses in the water, as well as rubbish.

Athletes started to take extra vitamin to increase the immune capability after being afraid of the reported bacteria and viruses.

Leonardo Gryner, deputy CEO of the Rio Organizing Committee, told Xinhua that the original target of reducing pollution by 80 percent is on track.

"The situation we had by the time we bid in 2009, roughly 12-13 percent of the sewage thrown into the bay was treated. Now it's over 50 percent. In 2016, we promise with 80 percent of treatment," he said.

He admitted that two major challenges facing the sailing event, one is the floating deribs, the other is people continuing throwing wastes into the bay. To solve them, the government is putting eco barrier to stop wastes entering the bay and eco boats to collect floating deribs.

"We never said the Guanabara will be clean (before the Olympics). It's a huge bay. We have challenges and problems here that will take 10 years or more to fix them all," he said.

"But the course of the Olympic sailing event will have water with good levels according to any international standards. We measured them every month," he added.