ROTTACH-EGERN, Germany - Volkswagen Group sold more than 3.5 million cars to customers world wide in the first half of 2010, the company's chief executive said on Tuesday.

January-to-June sales topped those of the same period in 2009 by about 15 percent, Martin Winterkorn said.

The group's core Volkswagen brand had sold significantly more than 2 million cars world wide, Winterkorn said.

He reiterated the Volkswagen group will see record car sales in 2010.

But this will not be achieved easily. Especially in Germany, business will become significantly harder in the second half of the year, Winterkorn said.

(Reporting by Irene Preisinger, Writing by Arno Schuetze; Editing by Leslie Gevirtz)