Abu Dhabi's Aabar Investments is preparing a bond that can be exchanged for shares in Italian bank UniCredit SpA, a source familiar with the matter said on Monday.

A spokesman for Aabar, which has a stake of just over 5 per cent in Italy's biggest bank, declined to comment.

Earlier on Monday Bloomberg said Aabar was looking to raise at least 1 billion euros ($1 billion) by selling bonds that can be exchanged for shares in the Italian lender.

The report, citing people with knowledge of the matter, said Aabar could double the deal size if there was demand.

At 1451 GMT UniCredit shares were down 0.7 per cent while the European banking sector was down 0.1 per cent.

At current stock market values, Aabar's stake in UniCredit is worth around 1.8 billion euros.

The deal could be announced as early as Tuesday, Bloomberg reported.-Reuters