Which? wants the government to retain package holiday protections.
It is concerned a rush to review EU laws could leave holidaymakers with weakened protections.
This applies to when trips impacted by last-minute changes from package operators or suppliers.
It sees hundreds of complaints from people annually who suffer hotel downgrades,.
Recent cases include honeymooners whose dream trip was ruined when they were switched from a luxury resort to a lower standard alternative.
The Package Travel Regulations (PTRs) allow compensation in instances like this.
However, these protections are at risk.
Which? understands the government is planning to consult on changes to the regulations soon.
Which? Calls on the government to preserve these protections for UK and international holidays.
It also believes they should be enhanced.
Jo Rhodes, Deputy Editor of Which? Travel, said: “Alarmingly, there is a real danger protections relied upon by millions of travellers every year are at risk.”