Football legend Ronaldo, a member of Brazil's World Cup organizing committee, said Thursday that only 30 percent of the infrastructure projects undertaken for the tournament would be completed.
Brazil promised a host of projects in conjunction with the World Cup to improve its roads, airports and urban transport networks.
But the country has struggled to finish even essential ones such as stadiums, and has shelved much of the rest.
"I think we're missing an opportunity. A series of investments were promised that won't be delivered. Only 30 percent will be delivered," two-time World Cup winner Ronaldo told a forum organized by newspaper Folha de Sao Paulo. (Also read: Are Brazil the true favourites to win the World Cup?)
He also elaborated on remarks last week in which he said he was "ashamed" of the delays in preparing for the tournament, which kicks off June 12.
"My shame is for the people, who were hoping for major investments, that's the great legacy of the Cup for us. They were expecting a lot and they're the ones most hurt by the situation," he said.
The former Real Madrid and Barcelona star also joked about Brazil's tense relationship with FIFA. The world football governing body has sharply criticized the host country's delays.
"I don't think FIFA are going to want to organize another Cup here. They're going to be traumatized," he said.
Ronaldo, who this week endorsed opposition Senator Aecio Neves for presidential polls in October, voiced sympathy with protesters angry over the more than $11 billion being spent on the tournament, but called for them to refrain from violence.
"Protests are always valid. But as soon as there are vandals taking part, people in masks, the security forces have to contain the offenders," he said.
Brazil was shaken by sometimes violent demonstrations that drew a million people into the streets last year during the Confederations Cup, a World Cup dress rehearsal.
New strikes and protests have erupted as the World Cup approaches, though they have been smaller than last year's.