In an unusually blunt public warning, a vice president of the International Olympic Committee on Tuesday called lagging preparations for the 2016 Games in Rio de Janeiro "the worst I have experienced."

John Coates, who has made six trips to Brazil as part of the IOC's coordination commission for Rio, said the Brazilians are behind "in many, many ways" and are in worse shape than Greek organizers were in preparing for the 2004 Olympics.

Despite the critical delays, the Australian said there is no backup plan and the games will take place in Rio.

Coates noted the IOC had taken the unprecedented step of embedding experts in the host city to help the local organizing committee deliver the games.

"The IOC has formed a special task force to try and speed up preparations, but the situation is critical on the ground," Coates told an Olympic forum in Australia. "The IOC has adopted a more hands-on role. It is unprecedented for the IOC, but there is no plan B. We are going to Rio."

Brazil has also come under fire from football's world governing body, FIFA, for long delays in construction of stadiums and other infrastructure and the overdue delivery of venues for the World Cup, which kicks off in June. Two years out from the 2016 Olympics, the situation on the construction front is just as bleak.

"We have become very concerned. They are not ready in many, many ways," Coates said.

Work hasn't begun at Deodoro, a complex for eight Olympics sports venues, and the course that will host golf's return to the Olympic program after more than a century doesn't have grass yet. Polluted waters are a big worry for sailing and other sports.

The IOC released a statement trying to defuse the tension following Coates' comments.

It said it was working "with our partners" in Rio, including establishing joint task forces, a local construction manager and a high-level decision-making body involving the IOC, the government and all key partners of the project.

The IOC said there would be more regular visits to Rio by executive director Gilbert Felli, the senior troubleshooter sent to the city last week as part of a series of actions to tackle the delays.

"Mr. Felli has received a very positive response on the ground in the past few days, and a number of recent developments show that things are moving in the right direction," the IOC said.

Coates said dealing with three levels of government in Brazil made it harder for local organizers than it was for the heavily criticized organizers of the Athens Games, which were also plagued by construction delays and earned a "yellow light" warning from then-IOC President Juan Antonio Samaranch.

"I think this is a worse situation than Athens," Coates said. "In Athens, we were dealing with one government and some city responsibilities. Here, there's three.

Rio organizers responded by releasing a statement saying they know what needs to be done and are focused on delivering the games. They said there have been "unequivocal signs of progress" in preparations.

"It is time for us to focus on the work to be done and on engaging with society," the Rio committee said. "The support of the International Olympic Committee is also crucial. We have a historic mission: to organize the first Olympic and Paralympic Games in Brazil and in South America. We are going to achieve this. In 2016, Rio will host excellent games that will be delivered absolutely within the agreed timelines and budgets."