COPENHAGEN - The Rio 2016 Olympics bid team formally complained to the International Olympic Committee on Wednesday after the city was criticized by an official from the rival Madrid bid.

Spanish Olympic Committee vice president Jose Maria Odriozola reportedly called Rio "the worst bid'' of the four candidates.

Spanish news agency Efe on Wednesday also quoted Odriozola as saying Rio had security issues, and its status as a favourite was based on marketing and sentimentality.

In a statement to The Associated Press, Rio bid organizers said the criticism was "totally unacceptable.''

"His comments are totally unacceptable and we are lodging a formal complaint to the Ethics Commission,'' the statement said. "This gentleman is clearly out of step with the report of the IOC's own Evaluation Commission.''

The spat flared two days before the IOC votes to decide which city will host the 2016 Summer Games and less than 24 hours after Olympic officials reminded the four candidate cities - Chicago, Madrid, Rio and Tokyo - not to target rival bids.

"We would remind all cities that they must be careful of what they say,'' the IOC's communications director Mark Adams said. "They must not criticize other bids.''

Madrid official Odriozola's comments were reported as the Spanish team travelled to Copenhagen Wednesday, as the last of the quartet to arrive for final lobbying.

"At this point, the IOC is not going to risk it and take the Games to a site where it doesn't have total confidence that it can be done well,'' said Odriozola, who is also president of the Spanish athletics federation.

The IOC's evaluation team issued a report this month after visiting all four candidates earlier this year.

It stated its confidence in three cities' security plans, but withheld total approval for Rio which has a reputation for high levels of crime. It did praise Rio's efforts for engaging the police and communities in social projects centred on sport.

Rio's complaint is being directed to French lawyer Paquerette Girard Zappelli, who is secretary to the eight-member ethics panel which monitors bidders' behaviour.

The panel includes four IOC members and four people from outside the organization, including Peruvian diplomat Javier Perez de Cuellar, the former United Nations secretary-general.