RIO DE JANEIRO — Triathletes swam in waters off Copacabana Beach Friday ahead of weekend Olympic test events, despite published warnings that water in the area was “unfit” for swimming.

The website of the Rio de Janeiro environmental agency said the water, which has been declared unfit 10 previous times this year, was unsafe based on the results of a Monday water test.

Officials publicly insisted athletes were safe and stuck to the competition schedule.

The Rio environmental agency didn’t respond to requests for comment, but the situation prompted new concern about Rio’s polluted waters. On Thursday, The Associated Press released the results of a five-month investigation that showed that Olympic venues are rife with disease-causing viruses and bacteria.

Over 150 athletes are competing in an Olympic qualifier and Paratriathlon starting Saturday.