"Across all the different disciplines, we are something like 55 per cent European, and we're 26 per cent UK, and 19 per cent in the rest of the world," said Foster, speaking at the World Architecture Festival (WAF) in Berlin last week..
"And for me, that is a cause of great celebration. I was sharing with my partners with only today that it's in a way always been like that."
Foster made the comments during an acceptance speech for his Contribution to Architecture award, at the WAF gala dinner.
Recalling the early days of his studio, which was founded in London in 1967, Foster said talent from Norway, Switzerland and Israeli was represented.
"In that sense, I think I've always been out of step," said Foster. "So I celebrate in the face of the madness of Brexit being out of step, and [I'm] proud to be here in Europe and celebrating the European nature of this venue."
Foster + Partners declined to comment on its staff retention plans following the Brexit vote. The architecture firm – the 14th largest in the world – has offices in Dubai, Madrid, Abu Dhabi, Beijing, Hong Kong and New York, amongst other locations.
WAF celebrates "global nature" of architecture
During his speech, Foster also praised the World Architecture Festival for offering a "connected global experience".
The festival, now in its 10th year, aims to showcase the best architecture from around the world. This year, it saw prizes for excellence awarded to projects in 21 countries.
Top awards went to a prototype of for an earthquake-resistant home in China and a proposal to redevelop a dilapidated fish market in Australia. The event took place at Arena Berlin from 15 to 17 November 2017, and coincided with the Inside festival of interiors.
"This is the only event which celebrates the global nature of architecture," said Foster.
Foster warned against post-Brexit talent crisis
Earlier this year Foster warned that Brexit could leave the UK's architecture industry with a talent crisis.
His stance on Brexit chimes with many of the industry's key figures, including architect David Chipperfield, who said the UK's departure from the European Union will isolate the industry.
Chipperfield was also among a group of eminent British architects who demanded clarity on the status of EU nationals working in the UK following Brexit. John Pawson, Michael and Patty Hopkins, Amanda Levete, Ron Arad, Will Alsop and Eric Parry all signed the open letter sent to The Guardian newspaper.
Almost half of all architects working in London come from overseas, according to a survey conducted for Dezeen. The results found 33 per cent of architects in the capital's firms come from the European Union, the European Economic Area or Switzerland – highlighting the industry's reliance on overseas workers.
Redundancies at Foster + Partners amid Brexit uncertainty
Foster + Partners laid off nearly 100 workers earlier this year, with many speculating the redundancies came amid uncertainty in the industry following the EU Referendum vote. But the firm claimed the move was instead down to the simultaneous completion of a number of projects.
"Foster + Partners has grown significantly over the last two years with a record number of projects many of which are now close to completion," the firm told Dezeen at the time.
"This, coupled with some uncertainty in the construction market, has led us to make some adjustments to our practice, which regrettably includes some redundancies enabling us to balance numbers with our current and foreseeable workload."