Mobile point-of-sale and payments company SumUp recently raised a big round of Series B funding from Groupon and American Express to accelerate its growth and continue to differentiate itself from its European rivals iZettle and payleven.

Today, the company announced that it is expanding the Series B round with a strategic investment from BBVA Ventures, the corporate venture arm of multinational banking group BBVA.

Banco Santander, the largest bank in the Eurozone, recently pumped more than $6.6 million into iZettle in a similar move.

The investment from BBVA, which has Spanish roots dating all the way back to 1857, will serve to help SumUp establish a stronger position in Spain and Portugal – where the startup is already present – and expand its availability to South America down the line.

With headquarters in Bilbao, Spain, BBVA provides financial services in more than 30 countries and has emerged as one of the leading players in South America. Its investment arm has $100 million to back financial service startups from all over the globe.

SumUp declined to disclose the exact size of BBVA Ventures’ investment beyond that it is a continuation of the Series B round.

The startup’s co-founder, Jan Deepen, who is responsible for its international expansion, comments:

We are delighted to bring on BBVA Ventures as a new financial investor. International expansion is a key component of our growth story. Having BBVA as a strong partner at our side as we expand to regions beyond Europe – in particular South America – is invaluable.

SumUp helps merchants accept debit and credit card payments from customers with their smartphones and tablets. At present, SumUp only supports payments via Visa and MasterCard.

The fresh cash will also be used to hammer out its end-to-end payment solution, which encompasses a certified payments gateway as well as proprietary terminal hardware and operations systems.

The previously-announced Series B financing round follows another ‘double-digit million Euro’ (reportedly $20+ million) Series A round closed in the second quarter of 2012, from b-to-v Partners, Shortcut Ventures, Tengelmann Ventures and a group of business angels.

SumUp was founded in 2011 by Deepen, Daniel Klein, Petter Made, Stefan Jeschonnek and Marc-Alexander Christ. The company currently boasts major offices in Berlin, London, Dublin, Madrid, Milan and Moscow.

Its services are currently available in European countries such as Germany, UK, Ireland, Spain, Italy, Austria, the Netherlands, Belgium, Portugal, France and Russia, but you’ll likely find some South American countries in that particular list in the near future.