Kheraj shocks the City as he walks out of Lazard

One of the most senior executives at Lazard has shocked the City after revealing he was to quit the investment bank after only six weeks. Naguib Kheraj joined Lazard at the beginning of January as chief executive of the international business, a role created specifically for him.

The bank, which recently hired Lord Mandelson as a special adviser, disclosed the news yesterday morning and is not expected to look for a replacement in the short term.

The move came after Mr Kheraj found it impossible to juggle his duties with his outside activities. He is understood to have told friends that he was "disappointed" by how his time at Lazard turned out but that there had been no bust up with the firm.

Lazard confirmed that Mr Kheraj had departed "in order to concentrate on his philanthropic activities with the Aga Khan Development Network and his other personal interests".

Publicly, the outgoing executive said he was "very sad" to be leaving, and had not taken this decision lightly. "I underestimated the difficulty of managing my external activities in a way that would enable me to be properly engaged in an executive role and have realised that it is not possible to fulfil my responsibilities to Lazard to the best of my ability whilst maintaining my personal commitments."

He holds a series of roles outside of Lazard, including chairmanship of the national committee of the Aga Khan Foundation, and is chairman of the endowment committee of the Aga Khan Development Network. As well as being a member of the board of governors of The Institute of Ismaili Studies, he is also on the investment committee of the Wellcome Trust and the board of the Fulbright Commission.

Lazard's statement added: "We understand and respect Naguib's reasons for stepping down. He was a friend of the firm before he joined and will continue to be a friend."

Mr Kheraj started in the City in 1986 and after roles at Robert Fleming and Salomon Brothers joined Barclays, where he worked for a decade in a series of senior roles. These included management positions in its wealth management, institutional asset management and investment banking arms before his promotion to group finance director. He later joined joint venture JP Morgan Cazenove as chief executive. He was a client of Lazard at both JP and Barclays.

Sources close to Mr Kheraj believe he will consider board roles in the banking or asset management sector in the future.