A NatWest Group spokesperson said: "Following careful consideration, and having previously paused all activity, NatWest Group has today withdrawn its membership of the CBI with immediate effect.

"British business needs a strong representative voice. Given the extremely serious allegations made against the CBI, we no longer have confidence that it can fulfil this role at the present time."

BT Group said: "In light of the appalling allegations made, BT Group has decided to suspend its membership of the CBI with immediate effect."

The John Lewis Partnership had earlier cited "further very serious and ongoing allegations" as the reason for quitting the organisation.

Insurer Aviva was first to reveal its hand on Friday, just moments after Sky News reported that abrdn, the FTSE 100 fund manager, was also considering its position with the organisation.

Fellow insurers Phoenix Group and Zurich swelled the exodus alongside the industry body the ABI while Virgin Media O2 also confirmed it had terminated its membership.

Asda, accountancy giant PwC and National Grid later confirmed they had suspended all activity with the business lobby group while Lloyds Banking Group was also understood to have done the same.

An AstraZeneca spokesperson said: "Following these grave allegations, we have decided to pause our engagements with the CBI while these are investigated."

The rush for the exit door came after the Guardian newspaper reported that a second woman had made a rape allegation - against two male CBI co-workers - building on the series of historic serious misconduct claims to have engulfed the body in recent weeks.

"In light of the very serious allegations made, and the CBI's handling of the process and response, we believe the CBI is no longer able to fulfil its core function - to be a representative voice of business in the UK,", Aviva said.

"We have therefore regrettably terminated our membership with immediate effect."

CBI president Brian McBride had previously admitted that a "handful" of its 190,000 members had departed since the crisis began.

They are known to have included, before Friday, the British Insurance Brokers' Association.

Shell is understood to have suspended dealings with the CBI last week.

The potential departure of abrdn would be acutely embarrassing for Mr McBride personally as he currently serves as a non-executive director at the firm.

Sky's City editor Mark Kleinman reported that the board had been debating whether to terminate its status as a CBI member once a CBI-commissioned review of sexual abuse allegations against staff members had been completed.

A source said that alternatively it could decide not to renew its membership when it expires at the end of this year.

A string of blue-chip companies, including Rolls-Royce and Marks & Spencer, have raised public concerns about the crisis.

Last week, the CBI sacked Tony Danker, its director general, after saying it had lost confidence in his ability to lead the organisation amid claims about his personal conduct.

Mr Danker told the BBC this week he had been "thrown under the bus" and said the allegations against him did not merit his dismissal.

He also apologised for making a number of CBI employees "uncomfortable".

Business leaders have lined up in recent weeks to denounce its handling of the crisis, saying it had been too slow to apologise and had erred by appointing an insider, Rain Newton-Smith, as Mr Danker's successor.

Read more from Sky News:
Wet weather leads to retail sales dip
MPs call for workers' rights watchdog to bolster labour protections
Massive spike in concert and festival scams, report finds

Three employees have been suspended, while a police investigation is under way.

The CBI said this week that the second phase of an inquiry by the law firm Fox Williams would conclude imminently.

"The board will be communicating its response to this and other steps we are taking to bring about the wider change that is needed early next week," the group said on Thursday.