HSBC has been accused by First Citizens, which acquired Silicon Valley Bank after its collapse, of breaking the law by poaching more than 40 employees from the failed American bank.

First Citizens is suing HSBC, which acquired the British arm of SVB following its sudden failure in March, for $1bn for "brazenly" seeking to "plunder" trade secrets, according to reports, which HSBC has declined to comment on.

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Claims in the lawsuit state HSBC and a former senior SVB banker co-ordinated the scheme, dubbed "Project Colony", to strip the "core of [SVB's] profitability engine" in the form of certain staff.

HSBC bought SVB UK for £1 in March, days after the implosion of its American owner, a regional lender based in California, due to its haemorrhaging of tens of billions of dollars in deposits from venture capital investors and start-ups worried by losses in its securities portfolio.

Weeks later, First Citizens, based in North Carolina, acquired most of the remaining business.

According to the lawsuit filed by First Citizens: "Just two weeks after First Citizens acquired SVB, defendants executed the first ‘wave' of their scheme, raiding 42 First Citizens employees around 9pm on Easter Sunday."

These employees went on to resign "en masse" over the next half an hour, with immediate effect, it claims, having been promised "great fortune" if they jumped ship.

It is claimed this mass poaching was orchestrated by David Sabow, a senior executive at SVB in the US, who joined HSBC "within days" of the UK deal, according to the lawsuit, filed in a federal court in California.

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Those former employees targeted had relationships and detailed information on clients that gave the Silicon Valley lender its advantage with tech clients, First Citizens alleged.

Using data from SVB, Sabow projected that a new unit staffed by the bankers he aimed to poach could generate profits of $66mn in its first year, rising to almost $1.3bn in year five, according to the complaint.

A spokesperson for HSBC declined to comment on Sabow's behalf last night, according to The Times.