* GM says lab work not related to the Chevy Volt
* GM Technical Center is sprawling campus
* Five receive medical attention, one taken to hospital (Updates with GM statement saying incident occurred in a test chamber)
April 11 One person was seriously injured Wednesday morning by an explosion at a General Motors Co laboratory near Detroit during a test of lithium-ion batteries for electric cars not yet in production, city and company sources said.
Five people received medical attention after the incident at the GM Technical Center in Warren, Michigan and one person was taken to a local hospital, GM said.
Warren Mayor Jim Fouts said he was told by Warren Fire Department officials that fumes from hydrogen sulfide caused an explosion inside a battery laboratory.
A man who suffered a concussion and chemical damage to his skin was apparently outside a containment area where tests were being conducted on a prototype battery, Fouts said.
"It was a major explosion," Fouts told Reuters. "At least one 8-inch (thick) door was blown out. What could have been a major catastrophic event was not so because of the quick work of the Warren Fire Department and GM officials."
The explosion, which occurred about 8:45 a.m. EDT (1245 GMT), also blew out at least three windows and, according to Fouts, about 80 people in the building had to be evacuated.
GM said in a Wednesday afternoon statement the incident occurred "inside a test chamber at the General Motors Alternative Energy Center during extreme testing of an experimental battery.
"Chemical gases from the battery cells were released and ignited in the enclosed chamber. The battery itself was intact. The battery tested and the incident have no connection with the Chevrolet Volt or any other GM production vehicle," GM said.
The Volt has been highlighted as a centerpiece in GM's push for more fuel-efficient cars and trucks.
Fouts said he was told that at no time was hazardous waste a threat to GM workers or the community near the GM Tech Center.
People familiar with the matter said the battery was being developed for future electric vehicles.
"Our efforts are focused on the well-being of our employees and we're happy that they are all accounted for," said GM spokesman Greg Martin. "One required treatment. We are working closely with on-scene authorities to investigate the incident."
"It's entirely premature to speculate on the cause or characterize the nature of the incident," said Martin.
GM said all areas of the Alternative Energy Center except for the battery lab and nearby offices will operate normally on Thursday.
The explosion follows another high-profile battery failure last month when Fisker Automotive's luxury sedan, the Karma, failed during testing by Consumer Reports. The Karma's battery, which was produced by A123 Systems, failed due to a manufacturing defect and A123 said it would send replacements.
An A123 spokesman declined to comment on whether the company's battery was involved in the explosion. He referred questions to a GM spokesman, who also declined to comment.
A123 makes the battery for the upcoming Chevrolet Spark all-electric car, which will debut in 2013.
American consumers have been slow to embrace electric and rechargeable vehicles, in part because of their additional cost. Battery safety concerns could slow their adoption further, although industry analysts said problems are not unusual when trying to develop new technologies.
Last year, U.S. federal regulators opened an investigation into the safety of the Volt's battery pack after its own tests uncovered fire risks. By January, NHTSA closed its probe without finding any defects and said it was satisfied with GM's fix to better protect its lithium-ion battery pack.
"Some critics will use this story to bring back to life the investigation into Chevy Volt fires from earlier this year," said Michelle Krebs, auto analyst with Edmunds.com.
"While this incident deserves some scrutiny - especially since workers were hurt - the fact is that this is the reason why new car technology undergoes rigorous testing, to try to ensure that episodes like this don't happen on the road."
GM suspended Volt and Opel Ampera production, due to weaker demand than anticipated, on March 19 and will resume production on April 16, a week earlier than previously announced, GM said on Wednesday. The Opel Ampera, which is basically the same car as the Volt, is sold in Europe.
The company continues to work to adjust Volt production to market demand, GM has said, and its production suspension is not related to quality issues on the Volt or Ampera.
Two years ago, GM said it was nearly doubling the size of its battery labs at the GM Tech Center, to 63,000 square feet. The GM Tech Center is a sprawling campus of office and research buildings and grounds in suburban Detroit. (Additional reporting by Deepa Seetharaman and Ben Klayman in Detroit; Editing by Gerald E. McCormick, Lisa Von Ahn, Sofina Mirza-Reid, Gary Hill and Richard Chang)