Mobile payment service iZettle says American Express has joined its list of financial backers. The latest funding round already included over £20 million from MasterCard and venture capital funds including Greylock Partners, Northzone and SEB Private Equity plus initial investors Creandum and Index Ventures.

iZettle will use the funding for product development and expansion into new markets.

Stockholm-based mobile payment service iZettle has announced it’s now able to accept American Express cards in Sweden and Finland. The company was already able to accept MasterCard, Visa and Diners Club payments via its card reader and app. 

iZettle’s reader plugs into an iPhone or iPad and turns it into a mobile payment terminal for ‘chip and PIN’ credit cards.

American Express, which recently launched its own online payments service for US residents, has now announced a partnership with mobile payment service Payfone. Payfone will combine its mobile authorisation and payment services with Serve, the new American Express payments platform.

Serve already gives customers in the USA a 'virtual wallet' that can be accessed online and via a mobile app.