Thousands of Eurostar passengers desperate to travel before Christmas filled the London terminal on Wednesday, forming snaking queues that prompted the train operator to urge others to stay away.
Eurostar issued a statement advising passengers still stranded following a three-day shutdown of the cross-Channel service not to come to the station until after 1:00pm (1300 GMT) "as the trains are full until that time".
Long queues stretched outside St Pancras International as increasingly frustrated travellers gathered early in the hope of getting to the continent ahead of Christmas Eve on Thursday.
Arguments began breaking out between passengers amid confusion as to who would be given priority on the trains heading to Paris and Brussels, which only resumed a limited service on Tuesday after an unprecedented suspension.
A Eurostar spokeswoman said passengers had been urged to wait until the afternoon "because we don't want people to be standing in the cold. We want to avoid the frustration. It's quite busy this morning."
After those with tickets from the weekend were put on trains on Tuesday, Eurostar announced that customers due to travel anytime up to Thursday would be let on trains on Wednesday and Thursday.
Emmanuel Orejas, 41, a Belgian businessman who had been waiting in London for two days with his family, expressed frustration that he was not given priority over passengers who were due to travel later.
"We have been left without knowing anything for several days. And now they are opening the doors to all passengers, even those with tickets for Wednesday," he told AFP.
However, a Eurostar spokesman insisted that priority would be given to people with tickets for Monday and Tuesday, adding that they expected 15,000 to travel on Wednesday, including "everyone who is here" at the station.
The normally high-speed Channel Tunnel service was brought shuddering to a halt on Friday by what a British spokesman called a fall of "fluffier" than expected snow, stranding tens of thousands of people both sides of the Channel.
A limited service resumed Tuesday and was due to continue Wednesday and Thursday, with a full service not expected until Christmas Day on Friday.