WASHINGTON  - U.S. regulators on Wednesday reviewed 10 complaints that fixes made to recalled Toyota Motor Corp  vehicles did not resolve unintended acceleration.

The National Highway Traffic Safety Administration (NHTSA) said it is reviewing reports that have been received since mid-February and are interviewing vehicle owners. The regulator said the allegations were unconfirmed.

David Strickland, the NHTSA administrator, said in a statement that the agency wants to get to the bottom of the matter and ensure that Toyota is doing everything possible to address the situation.

If Toyota owners are still experiencing sudden acceleration incidents after taking their cars to the dealership, we want to know about it, Strickland said.

Toyota had no immediate comment.

Jim Lentz, Toyota's U.S. sales chief, told Congress last week that he does not believe current recalls will address all cases of unintended acceleration.

NHTSA is again reviewing whether there are glitches with Lexus and Toyota electronic throttles. Toyota, which has hired an independent consulting firm to examine the issue, said as late as Tuesday that exhaustive testing has found no problems with that system.

Toyota said this week it had fixed more than 1 million of the more than 6 million cars and trucks subject to recalls in October 2009 and January. Recalls covered loose floor mats that can jam the accelerator and gas pedals that do not spring back as designed.

NHTSA said there were no explanations as of yet for the small number of new complaints, but was moving quickly to address them.

Congress sharply criticized the agency in hearings on Toyota safety for responding too slowly over the years to complaints about unintended acceleration and doing little about it until a related crash in California that killed four people in August spurred new scrutiny.

Six new reports alleging post-recall problems filed with NHTSA's consumer complaint database involved late model Camry, Camry XLE Matrix, Avalon, and Corolla. Camry and Avalon models were included in both recalls, while Matrix and Corolla were only part of the sticky pedal recall.

(Reporting by John Crawley)