Nationwide chief executive Graham Beale told Reuters that Nationwide wanted to strategically enter the small and medium-sized enterprise space.
He said: “If there's anything I could do that would accelerate our strategy it would be of interest. Within that context RBS is something which we will watch very carefully.”
Beale added: "There are clearly some enormous complexities there, otherwise that deal would have been done. We need to understand just what those issues are before we can be committal on the point."
Santander pulled out of a £1.65bn deal to buy the branches last month after it said the process of separating the business from RBS had been more difficult that it had anticipated.
Brussels set RBS a deadline of the end of next year to sell the branches as a penalty for the bank’s £45bn bail out by the UK government.
Beale said funding the transaction was not a concern.
He said: "If we were to do the RBS transaction of all the things I'd be concerned about funding wouldn't be one of them. If you look at the strength of our balance sheet we've got one of the strongest solvency ratios in the industry."
