Australia's IOC vice-president has delivered a devastating blast at the chronic delays in Rio de Janeiro's preparations for the 2016 Games and warned that the situation in the Brazilian city is "critical".

John Coates, who is president of the Australian Olympic committee (AOC), described the preparations for the 2016 Games as "the worst I have experienced" and "worse than Athens [the 2004 hosts]".

Speaking at an Olympic Forum in Sydney, in comments reported on the AOC's website, Coates revealed that construction has not even started at some venues, that infrastructure work is significantly delayed and that water quality is a major concern.

Coates is a member of the co-ordination commission monitoring Rio's preparations and has made six visits to the city. He was also heavily involved in organising the 2000 Sydney Games.

He said: "We have become very concerned, they are not ready in many, many ways. We have to make it happen and that is the IOC approach, you can't walk away from this.

"The IOC has formed a special task force to try and speed up preparations but the situation is critical on the ground. 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."

Coates added: "The city also has social issues that need to be addressed."

He also claimed that Games organisers were "fobbing off" IOC inspectors when they asked for specific information, and that only two staff were working in the test event department with tournaments due to start this year.

Coates added: "No-one is able to give answers at the moment.

"Can they use the car parks in the village for recovery centres? What will be the time to take from this venue to this venue?

"All of those things, they're being fobbed off."

The IOC has not faced such a crisis with an Olympic host city since Athens in 2004, where work continued until the very last minute but was finally able to stage the Games.

Earlier this month sports federations demanded a back-up plan to Rio because of the chronic delays and IOC president Thomas Bach promised action to stave off the crisis, sending in Olympic Games director Gilbert Felli as a troubleshooter.

"It is about time for action," said Bach. "We share their concerns. We will address them. We will do everything we can do to make these Games a success."

Rio's mayor Eduardo Paes has hit back at the complaints saying the sports federations were making too many unnecessary demands but that he will not bow to their pressure.