Antonio Horta-Osorio is taking a break from his role as chief executive of part-nationalised British lender Lloyds Banking Group for health reasons, a source with knowledge of the matter told Reuters.
The source said Horta-Osorio's decision followed medical advice from doctors, but added that he was expected back at work before the end of the year.
"He's been suffering from fatigue due to over-work," said the source.
The board of Lloyds is set to discuss interim measures later on Wednesday.
Lloyds declined to comment on the matter.
Horta-Osorio took over as chief executive in March, joining from Spanish-owned rival Santander UK at the end of last year.
Since arriving at Lloyds he has quickly embarked on a restructuring programme which has entailed plans to axe some 15,000 jobs, halve Lloyds' international presence and sell off some 630 retail bank branches.
Lloyds has said it aims to make a decision by the end of the year on either a sale or spin-off of the 630 branches - which it has been ordered to sell by regulators as payback for a state rescue package during the credit crisis.
Britain ended up with stakes of around 40 per cent in Lloyds and 83 per cent in Royal Bank of Scotland after rescuing both during the original banking crisis with taxpayer bailouts, and RBS has also been told to sell off a host of assets.
City A.M. Reporter