To put this into context, Visa now values Earthport at almost 400% more than the market did before it emerged with its original deal.
Earthport has yet to say whether it plans to accept the latest deal.
In a brief separate statement noting the increased offer, Mastercard said it is considering its options and urged Earthport shareholders to take no action in response to the announcement by Visa, adding that a further announcement will be made in due course.
In early trading, Earthport shares were 9.8% higher at 42.60p, indicating that the bid battle has further to run.
-- Adds Mastercard statement, share price --