South Korea's Hyundai Motor said on Wednesday it had suspended sales of its new Sonata models in the United States due to door lock problems, sending its shares more than 4 percent lower.

The decision comes as rival Toyota Motor Corp has been struggling with a mass recall crisis since late January, which had spawned expectations that Toyota's tarnished safety record would shift consumers to more affordable Hyundai models.

We have halted the sale (of the new Sonata model) due to door-related defects, a Hyundai official said.

We're looking in to the problem and working on how to deal with it.

Earlier, local news service Moneytoday said that Hyundai Motor's U.S. unit ordered a halt to sales of the new Sonata after notifying dealers of potential problems with the front door locks, citing U.S. auto industry media.

Shares in Hyundai Motor shed as much as 4.3 percent shortly after the market open before trimming losses to be quoted down 3 percent at 113,500 won by 0051 GMT, versus a 1 percent drop in the wider market.

Hyundai was the only major automaker to increase sales in the battered U.S. market last year.

Hyundai's U.S. sales rose 8.3 percent to 435,064 units in 2009, while industrywide U.S. sales were down 21 percent. Its share of the U.S. market jumped to 4.2 percent from 3 percent in 2008.

This year it is targeting 4.5 percent market share in the United States, helped by popular new product launches and aggressive marketing.

(Reporting by Kim Yeon-hee, Junyoun Park and Cheon Jong-woo; Editing by Jonathan Hopfner)