Hundreds of UK bankers at JP Morgan and dozens from Goldman Sachs are on standby for relocation to EU offices by 29 March, regardless of parliament’s vote to delay Brexit.

The exodus is likely to be replicated across the Square Mile as investment banks, almost all of which are foreign-owned, put in place emergency measures to cope with a period of uncertainty that could stretch through to summer, depending on the outcome of votes in parliament this week.

About 400 JP Morgan bankers are ready for last-minute moves to rival financial hubs including Frankfurt, Luxembourg and Dublin as part of preparations for a no-deal Brexit, a source told the Guardian. It is part of the bank’s plans to shift staff “as late as possible” to avoid any unnecessary disruptions.

While Thursday’s parliamentary vote in favour of an extension to article 50 has not affected the existing relocation plans – given that an extension still requires EU approval – JP Morgan is understood to be watching developments carefully. In the meantime, affected staff, who primarily work across sales and trading, are “clear that they’re on standby”.

Goldman Sachs has a couple of dozen trading desk staff ready to be shifted overnight, a separate source confirmed. The US investment bank employs about 6,000 people in the UK, while as many as 700 could be relocated in the event of no deal. It is understood about 150 have moved to other offices in the EU so far, most of them EU27 nationals.

JP Morgan and Goldman Sachs declined to comment.

JP Morgan employees are also bound for Paris, Madrid and Milan. The bank, which employs about 16,000 people in the UK, recently opened a new office in Dublin, which has the capacity to host double its existing Irish workforce of 530.

Liam McLaughlin, an EY partner and the firm’s financial services Brexit lead, said it was not time for companies to back-pedal on their Brexit plans. “Over the last three years, financial services firms have invested significant time and resources in preparing for all possible scenarios, and our view is they are unlikely to halt their plans for a no-deal in hope of a possible extension.

“There would be a real operational risk if firms started to stand down their no-deal preparations now only to have to try to stand them up again if no-deal becomes a reality in two weeks.”

The latest Brexit tracker report by EY estimates that London is on track to lose about 7,000 jobs to the EU “in the near future”, while about 2,000 roles are being created on the continent and Ireland in response to Brexit.

The US bank Morgan Stanley is ready to transfer 150 UK staff to EU offices, including Frankfurt, Paris and Dublin, while Bank of America is ready to relocate nearly 200 front-office roles to Paris by 29 March from regional offices including the UK. About 200 of its back-office roles will also move to Paris in the long term, with 100 UK jobs already transferred to Dublin.

Figures published by capital markets thinktank New Financial earlier in the week found that financial firms were shifting nearly £900bn in assets and funds out of Britain to the EU as part of Brexit contingency plans.

In January, Barclays gained high court approval to shift 5,000 clients and €190bn (£162bn) in assets from the UK to Dublin, which will serve as its EU hub after Brexit. Royal Bank of Scotland, meanwhile, is on track to move assets worth £13bn – £6bn of client assets and £7bn in liabilities – from its UK business to Amsterdam.

The firms preparing themselves for no deal

Royal Bank of Scotland is to transfer £13bn worth of assets. Photograph: Neil Hall/Reuters

RBS

UK staff total: 68,600

Brexit moves: About 100 UK roles will be transferred to its EU hub in Amsterdam.

Barclays

UK staff total: 48,700

Brexit moves: Adding around 150 staff to its Dublin office through a mix of new hires and UK transfers.

Lloyds

UK staff total: 75,000

Brexit moves: A handful of UK staff will be transferred to the bank’s 300-strong Berlin office. It is also understood to be setting up subsidiaries in Frankfurt and Luxembourg.

HSBC

UK staff total: 41,000

Brexit moves: Up to 1,000 UK-based roles which primarily serve EU clients may be transferred to its Paris operations.

Citigroup

UK staff total: 9,000

Brexit moves: About 63 London-based staff are to be transferred to EU offices including Dublin, Frankfurt, Luxembourg, Paris, Amsterdam and Milan.

JP Morgan

UK staff total: 16,000

Brexit moves: About 400 UK staff will be transferred to EU offices including Frankfurt, Luxembourg, Dublin, Paris, Madrid, and Milan

Goldman Sachs

UK staff total: 6,000 in London

Brexit moves: Up to 700 UK staff could be transferred to EU offices in the event of a no-deal Brexit.

Morgan Stanley

UK staff total: 6,000

Brexit moves: 150 UK staff to be transferred to EU offices including Frankfurt, Paris and Dublin.

Bank of America Merrill Lynch

UK staff total: 6,000

Brexit moves: About 100 UK jobs have already been transferred to Dublin. Nearly 200 front-office roles will shift to Paris by 29 March from regional offices including the UK, while around 200 back-office roles will move to Paris in the longer term.