SAN FRANCISCO (Reuters) - Square Inc (>> Square Inc), the payments company led by Twitter Inc (>> Twitter Inc) Chief Executive Jack Dorsey, has launched in the United Kingdom in its first European foray.

The San Francisco-based company said on Tuesday that small-and medium-sized businesses in the U.K. would be able to use Square's credit card reader to accept payments on mobile devices. The feature helps small merchants and self-employed professionals complete credit card transactions without a cash register or expensive software.

Square estimated that, while more shoppers were choosing plastic over cash, about half of the U.K.'s 5.4 million small businesses do not yet take card payments.

Reuters reported in July that Square had incorporated a business called Squareup Europe Ltd in Britain and the company had been testing its payment system in London.

Square last year added Paul Deighton to its board of directors, an effort to establish its footing in the U.K. Deighton is a member of the House of Lords and previously served as Britain's commercial secretary to the treasury.

Square, which went public in 2015, also operates in the Canada, Japan and Australia, as well as the United States.

While the company has largely focussed on growing in the United States, startups around the world have launched similar services. In Europe, it would be competing with well-established companies such as the U.K.'s SumUp, which is backed by Groupon Inc (>> Groupon Inc), and Sweden’s iZettle. The United States' PayPal Holdings (>> Paypal Holdings Inc) has been in Britain for years.

As it exports its flagship payments globally, Square has also been expanding into new businesses, including financial software and business loans. The company's lending division, called Square Capital, analyzes data from its merchants payment flows and offers those that qualify short-term loans at a fixed rate.

Square is also looking to attract larger companies, which process more sales and could generate more revenue for Square. It processed $50 billion in payments last year.

Square's U.K. launch comes as Britain's burgeoning financial technology sector faces some uncertainty in light of the country's decision to leave the European Union.

(Reporting by Anna Irrera in New York and Heather Somerville in San Francisco; Editing by Leslie Adler)

By Anna Irrera and Heather Somerville

Stocks treated in this article : Groupon Inc, Twitter Inc, Paypal Holdings Inc, Square Inc