Four passengers were handed £10,000 fines each after failing to declare they had arrived in the UK from a "red list" country, police said.
West Midlands Police said the offenders were caught after landing at Birmingham Airport on Monday, the first day that tougher border rules came into force.
Six passengers who had also flown to Manchester Airport - not one of the designated airports - had to be transferred to Birmingham for hotel quarantining after spending time in a "red list" location.
From Monday, travellers arriving in England who have been in a country at high risk of coronavirus variants in the past 10 days must declare this on a form and isolate in a hotel for at least 11 nights at at an initial cost of £1,750.
Temporary Assistant Chief Constable Chris Todd told a meeting held by West Midlands Police's strategic policing and crime board: "By midday (Monday), on the first day of implementation, we have received six passengers who had declared travelling from a red list country, who were taken to the quarantine hotel.
"We also had four passengers who were identified as having travelled from a red list country, that hadn't declared it.
"So there are some people who have attempted to hide their routes but that's not worked out.
"They were identified and received £10,000 fines as a result."
There are 33 countries on the Government's "red list", including Portugal, the United Arab Emirates, South America and southern Africa.
The government has banned direct flights from those locations to the UK. The four people fined had flown to Birmingham via a country not on the list.
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Only people who are UK or Irish nationals or UK residents are allowed to enter the UK from a "red list" country, and those returning must arrive at one of five airports.
Meanwhile, on Tuesday it emerged that guests will be charged an additional £152 daily fee if they are forced to extend their stay due to a positive coronavirus test.
A positive result from a test taken on day two will lengthen a traveller's stay by two nights at a cost of £304.
If the day eight test returns a positive reading, the guest must remain in their room for an additional eight nights and pay £1,216.
