Ferry operators are being accused of an "opportunistic" threat to cut off routes to Europe if they're forced to pay compensation for cancelling sailings.
The bosses of Irish Ferries, Stena Line and Brittany Ferries wrote a joint letter to Taoiseach Leo Varadkar in July.
It was released under the Freedom of Information Act to The Sunday Business Post.
They say it's not fair to order them to pay out when direct ferries to the continent are cancelled -- saying customers still have the option of driving through the UK.
Last year Irish Ferries cancelled a large number of sailings to France after a shipbuilding firm failed to deliver its new ferry, the WB Yeats (pictured), on time.
In January this year, the National Transport Authority ruled Irish Ferries would have to pay compensation to thousands of customers affected.
The ferry companies said offering customers a choice between the refund or an alternative route through the UK has been the “long-established norm” in the sector when direct routes are cancelled.
It said the NTA ruling means they will be required to offer compensation of up to 50% of their fare plus a new booking on a direct route.
In the letter sent to the Taoiseach, Tánaiste and Transport Minister in July, ferry operators called for the Government to lobby on their behalf.
“If you in Government and we as ferry operators all want to maintain direct ferry services between Ireland and the Continent – which is even more relevant today given the current wave of concerns over Brexit – it is critically important that the Irish Government starts lobbying now with the ferry sector to ensure the CJEU does not close direct ferry links to the Continent,” it reads.
Labour Party Senator Kevin Humphreys, the party's spokesman on transport, says the operators should withdraw their letter.
"The three main ferry operators are exploiting a particular difficulty finds themselves in in relation to Brexit and is seeking an interpretation of legislation that suits themselves," he said.
"I think it's unfortunate, I think we should be working together to get the best outcome for Irish consumers -- let's see the outcome of the judicial review that's onging," he added.