RIO DE JANEIRO, April 17 (Xinhua) -- Former Brazil striker turned politician Romario says he doubts Brasilia's Estadio Nacional World Cup venue will be ready in time for its scheduled May 18 opening.

The stadium's deadline was extended by four weeks earlier this month after local organizers blamed rain for delaying the final phase of construction.

But the venue is still without a playing surface and Romario said officials could not guarantee its completion date.

"This is not a novelty because it's happening in all of the 12 stadiums that are hosting the (2014) World Cup," Romario said.

The former Barcelona frontman also criticized the stadium's budget, which has reached 600 million US dollars, more than double the original estimate.

"None of this would have been the case if construction work had begun earlier and budgets were more in line with the country's reality," he said.

Estadio Nacional is scheduled to host the opening match of the FIFA Confederations Cup between Brazil and Japan on June 15. The tournament is considered a warm up for the World Cup a year later.