Washington, Feb 17 (DPA) US authorities sought documents from Toyota Tuesday over its handling of a series of safety recalls, part of a fresh investigation into the beleaguered carmaker's conduct.

The US National Highway Traffic Safety Administration (NHTSA) is looking into whether Toyota Motor Corp acted quickly enough in responding to safety concerns over sticky accelerator pedals and faulty brakes in a number of models.

"Safety recalls are very serious matters and automakers are required to quickly report defects," US Transportation Secretary Ray LaHood said in a statement.

Separately, Toyota said it would briefly halt production at two plants, one in Texas and one in Kentucky, because of a backlog of vehicles at dealerships. The Japanese manufacturer's sales tumbled in January amid the recall controversy.

Toyota is required to hand over documents to the NHTSA showing when and how it learned of the defects, which have led the world's largest carmaker to recall more than 8 million vehicles worldwide over the past few months.

The Transportation Department on Monday said the number of deaths linked to unexpected acceleration by Toyota cars had risen to 34 in the United States. The updated figure followed a wave of publicity about the problem.

Toyota will stop production at its Kentucky plant Feb 26, and likely also for two days in March and one day in April, spokesman Mike Goss said. Its Texas plant will halt production during the weeks of March 15 and April 12.

The production stops follow similar US production halts earlier this year for safety recalls.