WorldFirst CEO Jonathan Quin said in a letter sent out to clients that was seen by Reuters that the company "will continue to operate as a UK-headquartered and regulated business with global operations" while becoming a wholly-owned division of Ant Financial.

Ant Financial declined to disclose the terms of the purchase.

Media reports first surfaced in December that Ant Financial was in talks to purchase WorldFirst. The Financial Times said earlier this month a potential deal would be valued at $700 million (£546 million).

Ant Financial is an affiliate of Alibaba, China's largest e-commerce company. Best known for Alipay, a payment service for making online purchases, it has steadily become a financial service provider that offers lending, savings, and other products for consumers.

The company reached a valuation of $150 billion (£117 billion) in mid-2018, sources said, ramping up anticipation towards an IPO.

It has attempted to expand overseas by launching Alipay in locations popular among Chinese tourists, and by making overseas acquisitions, primarily in Southeast Asia.

Ant Financial ran into problems when its plan to purchase MoneyGram, a U.S. based money remittance provider, was blocked by regulators in Washington on national security grounds. The thwarted deal marked a year of escalating tensions between the United States and China over technology and trade.

(This story corrects the fourth paragraph and first bullet point of an earlier version to say $700 million, not £700 million)

(Reporting by Josh Horwitz and Brenda Goh; Editing by Muralikumar Anantharaman)