WASHINGTON — A House committee yesterday questioned the rigor of To-yota's sudden acceleration tests, challenging the automaker's commitment to finding the causes of safety problems that have led to millions of recalled vehicles.

The House Energy and Commerce Committee told Toyota executive Jim Lentz in a letter there is "an absence of documents" to show whether the company fully investigated the possibility of unintended acceleration. The committee asked who is involved with the testing and demanded quarterly reports detailing allegations of the acceleration.

Toyota spokeswoman Cindy Knight said the automaker will cooperate with the committee's request and is "quickly investigating verifiable complaints" from drivers. The company is already giving the committee regular updates, she said.

Also yesterday, members of the House Oversight and Government Reform Committee asked the National Highway Traffic Safety Administration for more details on steps the agency is taking to address the acceleration issues and for information on the number of complaints by Toyota drivers.