LA ROCHELLE, France--The French government accused South Korean car makers Hyundai Motor Co. (HYMLY, 005380.SE) and Kia Motors Corp. (000270.SE) of dumping, amid stronger sales for the two auto makers while local manufacturers see their market shares dwindling.

"The two brands Hyundai and Kia are competing with our manufacturers in unacceptable conditions of dumping," said Arnaud Montebourg, who heads the industry ministry and renamed it the ministry for "productive recovery."

The antidumping measures sought against Hyundai would come under a trade agreement sealed between the European Union and South Korea, he said.

He did not elaborate on the remarks, which came during an address to Socialist Party members in La Rochelle.

French car manufacturers Peugeot Citroen SA (PEUGY, UG.FR) and Renault SA (RNO.FR) have suffered from the economic downturn in France, which has led to falling sales across Western Europe. Over the past months, Peugeot has announced cost-cutting plans that included the closure of assembly lines and massive layoffs.

The EU-South Korea free-trade treaty was signed in July 2011 and took effect in May. Mr. Montebourg issued a statement earlier this month declaring South Korean car exports to the EU had jumped 50% in January and February compared to a year before. He said the increase was mainly in the segment of small, diesel-engine cars, a niche where French makers were traditionally strong.

He noted that the treaty provides for the EU to urgently look into any sudden rise in imports to one or several member states of products belonging to a sensitive sector, such as cars. Mr. Montebourg wants the EU to look into the trade imbalance and to come up with a plan of "new action" if it turns out that there is a deep trade imbalance in France's disfavor.

According to European automobile manufacturers' association ACEA, Hyundai and Kia together sold 391,511 cars in the European Union in the first half of this year, up 17% from the first six months of 2011. The two brands together increased their market share to 5.9% in the first half of this year, from 4.7% a year before.

Recent data from CCFA industry group showed sales of personal cars in France fell 14% in the first seven months of the year. Sales from Hyundai group in France rose 30% from the same period a year ago, while sales of Peugeot and Renault fell 20% and 17% respectively.

A spokesman for Kia Motors said Sunday an official response will be available Monday morning. Hyundai Motor couldn't be reached for comment.