MUNICH (Reuters) - Volkswagen's <VOWG_p.DE> truck division aims to significantly increase its profitability this year as deepening cooperation between the MAN and Scania brands and improving overseas markets spur business, it said on Monday.

Volkswagen (VW), which launched a new truck & bus division in 2015 to challenge global rivals Daimler <DAIGn.DE> and Volvo <VOLVb.ST>, is targeting a long-term operating margin target of 9 percent, up from 6.1 percent last year.

"We are not striving to become a volume champion, we want to be the most profitable ones," chief executive Andreas Renschler told journalists, referring to improving markets in Western Europe, Russia and China.

But finance chief Matthias Gruendler made clear a significant improvement in financial results requires a rebound in the key Brazilian market where the VW division commands a 37-percent share of the country's commercial-vehicles market.

Overall truck and bus sales in Brazil have been falling for four years but demand is expected to rebound slightly in the second half of the year amid the improving economy with a chance for stronger growth in 2018, Gruendler said.

"Brazil has always been an important market and is characterized by a high degree of cyclicality," chief executive Andreas Renschler said.

Under Renschler, who ran Daimler Trucks before joining VW in February 2015, Europe's largest automotive group has also been seeking to expand its footprint in international truck markets.

Last year, VW announced a stake purchase in U.S. truck maker Navistar International Corp <NAV.N> which may earn the German group access to the vast North American truck market, and is also in talks about finding a new partner in China.

"We are currently in discussions about different opportunities," Renschler said. "All options are open" including a possible increase in MAN's <MANG.DE> stake in China's Sinotruk <3808.HK> and finding a new partner.

(Reporting by Andreas Cremer and Irene Preisinger; Editing by Maria Sheahan)