Staff at the high-street chain are made up of 110 different nationalities, with 65 per cent of those from outside the UK being EU citizens, she said last night.
“I would say that one in 50 people that apply to our company to work is British,” she told the House of Lords Economic Affairs Committee.
Customer Maria Henriquez, 38, told the Standard said Brexit would be “dangerous” for the capital’s hospitality industry.
She said: “It’s completely unfeasible if they start to stop people working and say they can’t stay here.
“It doesn’t make economic sense to enforce people to leave, or not to allow them in, so many businesses will lose staff and revenue.”
The merchandiser, who works for H&M, added: “Around 80 per cent of my workmates are EU nationals, my company is Swedish. It just would not make sense.”
Greek national and mother-of-two Nana Varveropoulou, 40, said: “It’s very worrying. I don’t think they would ask me to leave, my children have British passports but it makes you feel very unwelcome.
“You go into so many places and a lot of the staff are EU nationals, from France, from Spain, I’m not sure places could cope without the staff.
“People come over here and they work hard to support the economy.”
Karolina, a Polish national, who has lived in London for six years said the situation was “concerning”.
She added: “I knew a lot of staff in Pret were EU nationals but not that many, I will come more often to support them.”
However, others claimed the chain should work to attract British applicants.
Anthony Binney, 43, who works in property said: “Why not take on British people?
“Pret has been here around 20 years and it’s always been like that. We’ve got British nationals who need jobs.”
Natasha, from Northern Ireland, who lives in west London, added: “It’s a controversial topic.
“I do think that if I have paid money into education and paid into the country then those people should be entitled to a job first. I don’t think anyone should be sent away but I understand it is a small island and resources are limited.”
Pret A Manager has had to defend its use of foreign workers in the past.
In 2011, the company was at the centre of a row with then Employment Minister Chris Grayling, who said it was “unacceptable” for fast-food chains to employ foreign staff at a time when unemployment in Britain had reached a 17-year high.
Pret responded by saying people of all nationalities were welcome to apply, and that in some stores, particularly in London, more non-UK born workers applied for jobs compared to British workers.