Barclaycard chief executive Antony Jenkins will take over retail banking in the UK, Europe and emerging markets, while Diamond will lead commercial banking and retain control of investment banking and wealth management.
Seegers joined Barclays in 2006 from Citigroup where he was head of consumer banking in Europe, the Middle East and Africa.
Barclays agreed a deal to buy Standard Life’s banking assets last week £226m to expand its British savings and mortgage operations.
In a statement released today, chief executive officer John Varley said: “I am sad these changes result in Frits leaving the group. Frits has had a transformational impact on our retail and commercial business globally.”