Firefighters in the World Cup city of Natal said they were concerned about some safety problems in the stadium set to host a match on Friday even as a bus strike in the city forced officials to scramble to find alternative transportation for some fans.

Lt. Christiano Couceiro told the UOL news portal that a Thursday inspection of the Arena das Dunas found some problems, including some missing guardrails to keep fans from falling and temporary seating that wasn't bolted to the structure.

He also said that an area with 11,000 temporary seats had not yet been inspected by his department. Mexico was scheduled to take on Cameroon at 1 p.m. local time (noon EDT; 1600 GMT) in the stadium.

Inspectors returned to the stadium early Friday, but Couceiro said FIFA officials barred them from entering the stadium.

FIFA didn't have an immediate response to the Natal fire department's concerns.

''On Thursday, we could say that 95 percent of ... the stadium was within regulations. I don't know if they've fixed things now,'' Couceiro told UOL. ''It could be by match time 100 percent of the structure is complete.''

The fire official said he reported his findings to the Rio Grande do Norte state security secretariat and told them that ''any incident that occurs in the stadium will be the responsibility of the organizers.''

Couceiro added that the areas where inspectors found problems should be blocked off from the public, and that is what would take place at any other venue holding a large public event.

Calls to Couceiro were not returned, but an official with the Natal fire department confirmed the problems in a telephone call. He spoke on condition that he not be named, saying he wasn't authorized to speak to the press.

Meanwhile, a bus strike that began Thursday in Natal forced the local government to find a fleet of school buses and other vans to transport fans to the stadium.

The city government is arranging for school buses and vans to transport fans, with shuttles running from malls and supermarkets to the stadium. The strike started Thursday.