FRANKFURT (AP) -- Hakan Samuelsson, chief executive of German truck maker MAN SE since 2005, has resigned with immediate effect, the company said Monday.

Samuelsson, 58, did not provide any reason for the decision, but in a statement the Munich-based company said he would "leave at his own request."

Georg Pachta-Reyhofen, who heads the unit MAN Diesel SE, was named interim CEO.

The statement added that Samuelsson hoped his decision would help the company to "quickly devote all of its attention to its core business and its further development. He is convinced that there should be a fresh start at the highest level of the company."

There was no mention of ongoing investigations into alleged corruption. MAN said earlier this year that prosecutors were looking into instances of alleged bribery to secure contracts within the company.

Investors appeared to welcome the news, with MAN shares up 3.1 percent to euro61.37 ($91.68) in late afternoon Frankfurt trading after the announcement.

Samuelsson joined MAN in July 2000 as chairman of its MAN Nutzfahrzeuge AG unit and was promoted to CEO in January 2005.

Before joining MAN, he worked for Swedish truck maker Scania AB from 1977 to 2000, joining its executive board in 1996 and overseeing development and production.

In July 2000 he was appointed chairman of the executive board of MAN Nutzfahrzeuge AG and also a member of the executive board of MAN Aktiengesellschaft, both in Munich.

In late October, the truck and bus maker said its third-quarter net profit fell 98 percent to euro6 million as demand for its products dropped amid the economic downturn and it took a charge for the acquisition of Volkswagen AG's Brazilian truck business.

The company booked euro40 million in charges during the quarter related to the euro1.3 billion acquisition in Brazil earlier this year. Revenue fell 14 percent to euro3.1 billion.

Total third quarter order intake, one measure of underlying business, fell 14 percent to euro2.7 billion.

The company said the impact of the recession would be evident in its diesel engine business and turbo machinery units over the coming quarters as well.

It didn't provide a more detailed outlook, but said its efficiency measures are having a positive effect and that it was confident of long-term growth prospects.

MAN also builds diesel engines, including those used to power oceangoing ships, along with compressors and turbines for energy and power generation businesses.