Ryanair says the majority of customers waiting for a refund from the airline because of flights cancelled due to the pandemic will have their cash by the end of the month.
The airline says it has trained additional staff to help clear the backlog after massive travel disruption caused by the pandemic.
March refunds have been processed and half of refunds due to customers in April have now been paid out.
They are promising all of May and the majority of June will be cleared by month end.
In a statement, Ryanair CEO Eddie Wilson said the company is pleased with the progress made but there are still some issues to be resolved.
Mr Wilson said: "Over 90% of passengers who booked directly with Ryanair and who requested a cash refund for travel between March and June will receive their refunds before the end of July.
"It is worrying however that a significant rump of our customers, who made bookings through unauthorised 3rd party screenscrapers or online travel agencies, have yet to receive their refunds because the OTAs gave Ryanair fake email addresses or virtual credit card details for these customers."
Mr Wilson says this issue demonstrates the need for further regulation of the online travel booking industry.
"We are highlighting this fact to the regulators in Ireland (CAR) and in the UK (CAA) as this demonstrates yet again why urgent regulation of unauthorised screenscrapers is needed to ensure that these unauthorised intermediaries provide airlines with accurate email addresses and valid payment details for customers," said Mr Wilson.
The airline chief said this is necessary so that airlines can administrate cash refunds more efficiently to customers.
"We will continue to process these cash refunds as fast as we can, and would encourage any customers who haven’t yet requested a cash refund, to do so with our Customer Service team and we will process their request as quickly as possibl," Mr Wilson said.
Meanwhile, the airline has said it has agreed on paycuts with Irish pilots.
The airline said the 20% paycut agreed would be restored over four years.