Credit Suisse First Boston (CSFB) is sole adviser to easyJet on a £400m (€642m) proposed acquisition, cutting out UBS Warburg, the other investment bank close to the low cost airline.

Both banks are corporate brokers to easyJet and together advised the carrier on its initial public offering and a secondary equity issue at the end of last year. But the company is using CSFB alone in its merger talks with rival Go.