NTT DoCoMo Inc. announced today that it plans to make an additional investment of up to $38.3 million in German mobile and interactive service provider Net Mobile AG, which it acquired in 2009 through its wholly-owned German subsidiary. Net Mobile plans to use the investment to buy a controllling stake in Bankverein Werther, a private German bank with strong electronic commerce and payment services.

A presence in the banking industry will allow Net Mobile to enhance its mobile payment platform, according to NTT DoCoMo. Net mobile already offers operator-billings systems such as premium SMS payments, and after the acquisition it plans to offer direct debit and credit card payments and also develop various means of settlement.

Japan’s NTT DoCoMo is an international mobile operator and provider of comprehensive mobility solutions. Net mobile operates primarily in Germany, Switzerland and the United Kingdom.