It is not yet clear whether European Union withdrawal talks, which had been due to start on Monday, will also now go ahead on Wednesday, although Brexit Secretary David Davis has said they will start "next week".
HSBC, which has 43,000 employees in Britain, said in January that it was planning to move "activities covered specifically by European financial regulation" to the EU, which would shift about 1,000 jobs out of the UK.
Brexit negotiators will discuss Monday Britain's financial obligations to the European Union as the long, complicated and potentially perilous process of the United Kingdom leaving the bloc finally gets underway.
Two months ago, the Prime Minister could have looked forward to Britain having a strong negotiating hand on Day One of Brexit talks; now it is hard to see how her position could be any weaker.
Nevertheless, it illustrated the challenge May will face in the remaining days before the European Union divorce talks begin: finding a position that satisfies both pro-European and eurosceptic factions of her party if she wants to remain in power.
Fighting for her political survival, May has been trying to strike a deal with a small Northern Irish Protestant party to avoid a second election that could delay Brexit talks and damage the $2.5 trillion economy.
The DUP, under Mrs Foster, is close to striking a deal with the Conservatives that would allow a beleaguered Theresa May to form a minority government in London.More news: GOP baseball shooter is dead
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Foster later said it was "right and proper" for the DUP to support May's legislative programme, which is due to be announced next week and will be the first formal test of her ability to govern. "It continues and when the deal is done, it will be done", a senior source in the Conservative Party said yesterday.
"We want to see a Brexit that works for everybody, not just for Northern Ireland", she said.
May gambled that a strong election win, as forecast by some pollsters, would boost her majority in the House of Commons in time for the Brexit talks, but instead, her party surrendered 13 seats in the lower chamber.
"We made the case to her that we would oppose any deal that undermined the Good Friday Agreement", he said.
Britain's Department for Exiting the European Union denied that the country has given up on its aim of discussing all aspects of its departure and future relations simultaneously.
"Our view is that a withdrawal agreement and terms of the future relationship must be agreed alongside each other", a spokesman for Britain's Brexit ministry said.
Britain's finance minister said Friday that jobs and growth should be the priority when Brexit negotiations begin next week, indicating that the weakened government in London might be softening its tone with Brussels. "The withdrawal and future are intimately linked".