Lynne Peacock, chief executive of NAB's British operations, told Business Daily that the bank was prepared to strike into Britain due to the recent share price crash.
Ms Peacock said in a December interview that NAB's British subsidiaries, which are Clydesdale Bank and Yorkshire Bank, might do well to acquire a stake in rival banks.
"We have built a strong organic strategy," she said. "If there are things out there that help us develop that faster or bigger then we should look at them."
However, she conceded: "But what we shouldn't do is look at businesses simply because the price is lower. Because something is cheap it doesn't mean it is the right thing to do."
But now it is believed that NAB is seriously considering an acquisition after market values of some British banks have dropped by over 40 per cent.
"I'm really ambitious to grow this business and I think we are doing that," Ms Peacock said.
Alliance & Leicester is among those that experts suggest may be of interest to NAB.