The total number of staff to be cut has not been finalized but could be as high as 90 people, the sources said, declining to be identified because the matter is confidential.

Goldman Sachs analysts in a recent research note said the bank could cut 15 percent of investment banking staff globally, amounting to some 3500 out of 23,300 employees.

A spokesman for Barclays declined to comment.

Jenkins took over in August after the departure of Bob Diamond, who left when the bank was fined for interest-rate rigging. The future shape and size of Barclays investment bank is considered the most critical part of Jenkins' review, as this business contributes more than half of group profits.

Jenkins is not due to unveil his "Project Transform" until February 12, but "Project Mango", as the investment bank revamp has been named by the unit's boss Rich Ricci, is close to being wrapped up.

Barclays hired a prestigious roster of veteran and expensive Asia investment bankers after the 2008 financial crisis, with the hope of forming a banking and equities business that would put the London-listed bank in the same league as Goldman Sachs and Morgan Stanley.

While the U.S. and European arms of the new Barclays muscled into Wall Street, the Asian operation was hit by delays in its equity platform roll-out, stiffer than expected competition from local firms, and a quick rebound in Asian markets that allowed rivals to regain momentum.

(Additional reporting by Steve Slater, Saeed Azhar and Michael Flaherty; Editing by Daniel Magnowski)

By Lawrence White