RIO DE JANEIRO — The Olympic waters in this city are more widely contaminated by sewage than previously known and pose a greater threat to athletes’ health ahead of next year’s games, according to new results from tests commissioned by The Associated Press.

Expanded analysis of Rio’s waterways shows that high viral and in some cases bacterial counts are found not just along shorelines where raw sewage runs into waterbodies, but far offshore where athletes will compete in sailing, rowing and canoeing.

That means there is no dilution factor in the bay or lagoon where events will take place.

“It’s going to increase the exposure of the people who come into contact with those waters,” said Kristina Mena, a U.S. expert in waterborne viruses. “If we saw those levels here in the United States on beaches, officials would likely close those beaches.”

In July, the AP reported that its first round of tests showed viruses causing stomach and respiratory illnesses and more rarely heart and brain inflammation at levels up to 1.7 million times what would be considered highly alarming in the U.S. or Europe.

The report prompted sports officials to promise they would do their own viral testing. Those pledges took on further urgency in August, after pre-Olympic rowing and sailing events in Rio led to illnesses among athletes nearly double the acceptable limit in the U.S.

Nevertheless, Olympic and World Health Organization officials have flip-flopped on promises to carry out their own viral testing in the wake of the AP’s July report.

At issue are two kinds of testing.

Brazilian, Olympic and WHO officials now say Brazil needs only to conduct testing for bacterial “markers” of pollution to determine water quality. That’s the standard for nations around the globe to monitor waterbodies, mostly because it’s been historically easier and cheaper.

“The health and safety of athletes is always a top priority and there is no doubt that water within the field of play meets the relevant standards,” the Rio 2016 Olympic organizing committee said in an emailed statement Tuesday. “Rio 2016 follows the expert advice of the World Health Organization, whose guidelines for Safe Recreational Water Environments recommend classifying water through a regular program of microbial water quality testing.”