Shares in High Street bank Alliance & Leicester have risen 3.3% after a press report said it had rejected a bid from France's biggest bank, Credit Agricole.
The Independent newspaper said the bank had rejected an informal offer made in the last fortnight, that valued it at almost £5.8bn ($10bn).
The paper said the £13-a-share offer was considered too cheap, but A&L's bosses would be tempted at £15 a share.
The rumours saw the bank's shares rise 40 pence to 1230p on Thursday.
It is thought that Alliance & Leicester did not have to make an announcement to the London Stock Exchange because the approach was informal.
The Independent reported that there was also a rival suitor in the shape of Santander, the Spanish owner of UK banking rival Abbey.
It is reported to have talked to A&L about a takeover deal worth more than 1400p a share, or £6.2bn.
Alliance & Leicester is regarded as one of the banking sector's most likely bid targets.
The bank has 5.5 million customers and employs 8,500 people in the UK.
It reported a pre-tax profit of £547m for 2005, down 7% on the previous year when its figures were boosted by the £52m profit from the sale of its payment processing business.