Toyota Motor Corp will voluntarily recall about 50,000 Sequoia sport utilities because the stability system could cause an unexpected problem with low-speed acceleration, the company said on Wednesday.

The National Highway Traffic Safety Administration (NHTSA) said it requested the recall, which comes 18 months after the agency began investigating the accelerator response in early 2003 models.

The case is the latest in a string of recalls triggered by government scrutiny of Toyota's response to consumer complaints and its handling of equipment and mechanical problems related to unintended acceleration.

The initial investigation in 2008 of Sequoia traction control and the stability system was triggered by more than 160 consumer complaints, NHTSA documents show.

Toyota said it has received no reports of crashes or injuries resulting from the problem with the stability feature, which calibrates engine output and brake pressure to help control a vehicle if it loses traction in turns.

But some complaints cited by investigators alleged that vehicles were almost struck in traffic because of the accelerator response issues, according to complaints cited by the safety agency.

In this case, a problem inside the heart of the skid-control program may cause a warning light to illuminate, Toyota said in a notice to dealers that was obtained by Reuters.

In limited cases, the stability system could activate at low speed, about 9 miles per hour, for a few seconds after acceleration from a stop. As a result, the SUV may not accelerate as quickly as the driver expects.

Toyota said in a statement on its website that it had to upgrade software in affected vehicles. It told dealers it was still working on a specific remedy and timetable.

Toyota plans to notify owners in May, including some 25,000 vehicle owners who have already had their vehicles serviced under warranty.

NHTSA spokeswoman Julia Piscitelli said in a statement that Toyota cooperated with an agency request to issue a recall.

Toyota said its decision was consistent with efforts to respond more aggressively to owner complaints following criticism by the Obama administration and Congress of its handling of major Toyota and Lexus recalls in October of 2009 and this year over unintended acceleration.

The latest recall covers about 50,000 vehicles manufactured early in 2003 in Indiana, the note to dealers said. Separately, Toyota is recalling about 1,500 2003 Sequoia's in Canada for the same reason.

In addition, NHTSA is investigating whether there are problems with electronic throttles in Toyota and Lexus vehicles and whether that issue could be related to unintended acceleration.

Toyota said its throttle systems are sound, but is also investigating the matter.

The action on the Sequoias follows a voluntary recall announced on April 19 involving 9,400 2010 Lexus GX 460s sold in the United States and Canada to fix a rollover risk problem with stability software.

That issue was first flagged by engineers at Consumer Reports.

Toyota shares closed off 15 cents at $76.84 on the New York Stock Exchange.

(Reporting by John Crawley and Soyoung Kim; Editing by Lisa Von Ahn, Bernard Orr)