The threat of a power vacuum at the top of Lloyds , whose chief executive is on sick leave, will overshadow the part state-owned British bank's third-quarter results on Tuesday.

Lloyds shocked investors last Wednesday with news Antonio Horta-Osorio, CEO since March, was ill with work-related fatigue and stress, adding the 47-year-old should return by the year-end.

With information scarce, there are worries Horta-Osorio may need longer to recover or may not return.

Finance director Tim Tookey, due to leave in February for another job, was appointed interim CEO, adding to worries that Horta-Osorio's executive upheaval since arriving has left Lloyds thin at the top, at a time when it faces several headwinds.

Exane BNP Paribas estimated Lloyds will make a third-quarter loss of 445 million pounds and Nomura predicts it will lose 513 million on the back of higher funding costs and losses on bad loans.

That would add to a first-half loss of 3.25 billion pounds, hit by compensation for customers mis-sold insurance products.

Lloyds has also been trying to sell 632 retail bank branches. New bank venture NBNK and Co-Op Financial Services have said they bid, although Lloyds has said it could spin-off the business if offers were too low.

Analysts have said there was no obvious replacement for Horta-Osorio. Standard Chartered finance director Richard Meddings, former JP Morgan banker Bill Winters and Lloyds non-executive director David Roberts have all been linked to the CEO post.

Lloyds shares fell 3.1 percent to 27.69 pence on Monday, less than half the 63.1 pence Britain paid for its 41 percent stake.

(Editing by Dan Lalor)