FRANKFURT Deutsche Post AG, Germany's largest postal services provider, may have cut prices to try to force competitors out of the market, the country's antitrust regulator said.
The German Cartel Office said it was investigating the group's letter deliveries following complaints from rivals.
"There are accusations that the prices that Deutsche Post charges its large customers for the distribution of letters do not cover the costs," the Office said on Monday.
The watchdog, which did not disclose who made the allegations, said it was investigating whether Deutsche Post was trying to push rivals out of the market or deter new entrants.
In the letter market, Deutsche Post competes with Dutch post and packages group PostNL.
Deutsche Post shares were down 1.85 percent at 15.35 euros at 1446 GMT.
"It seems some investors are fearing that this could have larger repercussions for Deutsche Post," said one trader, who declined to be identified.
A Deutsche Post spokesman said that another German regulator, the German Network Agency, had recently found no wrongdoing in Deutsche Post offering discounts on letters to corporate customers.
Delivering letters accounted for about 10 percent of Deutsche Post's first-half group sales of 27 billion euros ($35 billion), which also includes express delivery and logistics.
About 85 percent of letters shipped by that business unit are paid for by corporate customers.
($1 = 0.7785 euro)
(Reporting by Ludwig Burger, Andrea Lentz, Nikola Rotscheroth and Matthias Inverardi; Editing by David Holmes and David Cowell)