Belgium's national railway company, SNCB, is threatening to suspend trains to the coast if government rules on carriage capacity do not change.
As part of many new measures in the face of a third wave of COVID-19, only window seats can be occupied on trains to popular coastal destinations.
But in a letter to Belgium's federal government, Sophie Dutordoir, the CEO of SNCB, says that's "unmanageable."
The warning was sent to the government ahead of the Easter holidays, once again taking place under the umbrella of COVID-19 restrictions.
In Brussels, cafes and restaurants may only provide takeout services, people must return home by 10 p.m., and pupils will not return to in-person teaching after the Easter break.
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Non-essential travel remains allowed within the country, but masks must be worn on public transport and in public spaces.
In the letter, Dutordoir calls for the measures to be dropped or for the government to impose restrictions on where people can travel.
If the government does not act, the railway company says it may be forced to close the most popular lines for safety reasons.
It comes as a Brussels court says Belgium's federal government must rescind all its coronavirus measures within 30 days or face a 5,000 euro ($5,880) fine for each day it continues to breach the law.
People wait in line to board a train heading to the coast due to the warmer weather. /AP
The government has been using executive orders to prevent people from leaving the country, close establishments, and limit gatherings – but judges say the current legal basis is not good enough.
The ministerial decrees are currently issued under the Civil Safety Act 2007, which allows the state to intervene in "exceptional circumstances."
Vincent Van Quickenborne, the minister of justice, says rules will remain and the government will appeal.
In the meantime, work will continue on a new "Pandemic Law" that should provide the necessary legal grounding.
As Belgium suffers from a third wave of COVID-19, driven mostly by a variant that was first identified in the UK, more people are ending up in intensive care. In one week, a quarter more patients were admitted to ICU wards, than during the previous seven days.
In response to this added pressure on Belgian hospitals, the government has asked them to increase their spare intensive care capacity from 50 percent to 60 percent. More cases are expected before the new restrictions start to make a difference.
Of Belgium's 11 million people, 22,000 have died from COVID-19.