* Investment bank CEO Paul Calello suffers sudden illness
* EMEA CEO Eric Varvel appointed acting replacement
* Investment bank helped C.Suisse exceed Q2 forecasts (Adds details, background)
ZURICH, Sept 2 (Reuters) - Credit Suisse Group AG named Eric Varvel acting chief executive of its booming investment bank on Wednesday due to the "sudden and unexpected illness" of incumbent Paul Calello.
The Swiss bank said in a statement Varvel had many years of experience in the investment bank and would continue to be based in London and maintain his role as CEO of the bank's Europe, Middle East and Africa region.
Credit Suisse said Calello would remain as involved in the business as far as an intensive programme of treatment for the unspecified illness would allow.
"Paul and Eric will consult closely, working together and with me to set the strategic direction of the investment bank," Credit Suisse CEO Brady Dougan said in the statement.
"We have made significant progress in implementing our client-focused, capital-efficient strategy and we continue to have an exceptional opportunity to further develop and grow our key client businesses."
Market share gains in investment banking helped Credit Suisse beat second-quarter profit forecasts. (Reporting by Emma Thomasson; editing by Elaine Hardcastle)