German media and publishing group Bertelsmann confirmed its full-year objectives Thursday, reporting a strong first half crowned with a deal to increase its stake in publisher Penguin.

Bertelsmann said in a statement that its net profit reached 502 million euros ($597 million) between January and June, a 4.1-percent increase on the same period in 2016.

Operating, or underlying profit stood at 1.1 billion euros, slightly lower than last year, while revenues grew 2.1 percent to 8.1 billion euros.

Chief executive Thomas Rabe said the group had reached a deal with Britain's Pearson to expand its stake in publisher Penguin Random House, set for completion in the fourth quarter.

"Bertelsmann will possess a strategic three-quarters majority in the world's largest trade publishing group -- the best possible conditions for successfully further developing this core business," Rabe said. 

Elsewhere within the group, Bertelsmann said its subsidiary RTL had increased its share of German television audiences and its digital revenues had surged over the first half.

It also hailed the global success of subsidiary Fremantle Media's TV series, American Gods.

For the full year, the group was "confident about operating performance", expecting "higher revenues, continued high operating profitability, and group profit of over a billion euros," chief financial officer Bernd Hirsch said.