A passenger says she was left "shaking and upset" when she was told to cover up on a flight.
Emily O'Connor said cabin crew told her what she was wearing - a crop top and high-waisted trousers - was "inappropriate" and "caused offence".
She said the manager of the Birmingham to Tenerife flight and staff surrounded her, saying she must put a jacket on.
Thomas Cook apologised, adding it was "clear we could have handled the situation better".
Miss O'Connor, 21, from Birmingham, also said staff "did nothing" when a male passenger shouted "shut up you pathetic woman" at her and swore at her.
Flying from Bham to Tenerife, Thomas Cook told me that they were going to remove me from the flight if I didn’t “cover up” as I was “causing offence” and was “inappropriate”. They had 4 flight staff around me to get my luggage to take me off the plane. pic.twitter.com/r28nvSYaoY— Emily O'Connor (@emroseoconnor) March 12, 2019
She said she had passed through security, passport control and boarded the plane for the flight on 2 March before anyone commented on what she was wearing.
Miss O'Connor said the greeting staff on the aircraft told her to cover up, she sat down and then was told by the flight manager and four other staff she would be removed unless she put a jacket on.
She tweeted: "I was given a jacket by my cousin sitting at the front of the plane and they did not leave until I physically put it on.
"They made comments over the speaker about the situation and left me shaking and upset on my own."
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In another tweet, she said "a gent two rows behind me was wearing a vest top and shorts...yet clearly nothing was said to him".
Responding to a tweet saying it was unsuitable to wear underwear on planes, Miss O'Connor said she had bought the item in the "summer tops" section of Zara last year.
A Thomas Cook spokesman said the airline was "sorry" to have upset Miss O'Connor.
He said: "It's clear we could have handled the situation better.
"In common with most airlines, we have an appropriate clothing policy. This applies equally to men and women of all ages without discrimination.
"Our crews have the difficult task of implementing that policy and don't always get it right."
The airline said its policy states customers wearing "inappropriate attire (including items with offensive slogans or images) will not be permitted to travel unless a change of clothes is possible".
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