Tour operator TUI has extended the suspension of its holidays for the next six weeks.
The company, which previously suspended operations to May 14, said all trips would be cancelled up to and including June 11, and warned customers wanting cash refunds that its call centres are “incredibly busy”.
TUI also cancelled its Marella Cruises sailings up to the end of June, and postponed the launch of its river cruises until late November.
"Due to the ongoing situation regarding COVID-19, the Department of Foreign Affairs have advised against all but essential travel," the company said on its Irish website.
"Unfortunately, this means that we’re no longer able to offer TUI holidays travelling on or before 11 June 2020, or Marella Cruises sailings travelling on or before 30 June 2020.
"All other holidays are continuing to operate as planned and will be continuously reviewed," it adds.
Please read our latest travel info for holidays up to and including 11th June. Weâre trying our best to get back to as many queries as we can, in the meantime please visit our website where youâll find all the info you need https://t.co/huyC6rR0Ft pic.twitter.com/5wIaJkAPO1— TUI Ireland (@TUIIreland) April 29, 2020
TUI is the UK's largest tour operator, and a total of nearly 900,000 people have had their holidays cancelled, a spokeswoman told PA.
The firm has told affected customers that they will receive a refund credit for the full value of their holiday - it can be used to book another trip taking place before the end of October 2021.
Package holiday customers will receive an additional credit worth up to 20% of their booking.
TUI said customers who are “unable to accept” a refund credit can apply for a cash refund, but warned that its call centre staff are “incredibly busy” so waiting times are “considerably longer than usual”.
Simon Cooper, founder and chief executive of rival travel agency On The Beach, told PA last week that failing to pay cash refunds is “a bad idea for everyone concerned” as struggling companies will be forced to “massively increase” their prices for next year’s holidays to avoid bankruptcy.
The issue of refunds for cancelled flights and holidays has been fraught during the coronavirus crisis, as companies struggle to deal with unprecedented volumes of requests, and many travel firms suffering huge financial losses due to a collapse in demand.
In Ireland, the pandemic has already forced the closure of Rathgar Travel, USIT Ireland, Flyaway Travel and Cruises for You.
Package holiday legislation states that full refunds should be given within 14 days for cancelled package holidays.
Consumer group Which? found that none of the UK’s 10 biggest holiday companies or 10 most popular airlines are offering full refunds within the legal timeframe, and some are refusing to provide refunds altogether.
"We're still complying with the government's social distancing rules, which means our customer service teams are working from home," TUI Ireland said on Twitter.
"We're receiving an extraordinarily high volume of contact, so we're still kindly asking that you don't call or message us unless it's absolutely urgent.
"We'll be in touch to discuss your options."
TUI Group, Europe's biggest tour operator, said beach holidays for its Irish and British customers would be cancelled until mid-May due to travel restrictions caused by the coronavirus pandemic and uncertainty about when those will end.