By Alex Stevenson
The coalition is to press ahead with its reforms to the banking system by implementing the Vickers report's proposals in full.
Business secretary Vince Cable said he and chancellor George Osborne had come to a "common view" over the need for reform after a year of intensive lobbying against the changes by the City.
"We've treated this as a joint exercise and we've come to a common view," Mr Cable told BBC1's The Andrew Marr Show.
"We just cannot risk a repetition of that financial catastrophe that we had three years ago."
He said Britain's big banks were at the "very centre" of the financial crisis and needed urgent reform.
"We are going to proceed with the separation of the banks, the casinos and the retail business lending parts of banks – something I and the Liberal Democrats have pushed at for a long time," Mr Cable said. "It's now going to happen.
The ICB's initial proposals to split the banks in its interim report in April prompted a storm of opposition.
RBS chief executive Stephen Hester told the Commons' Treasury committee reflected those of many in the City when he warned: "I believe that creating a ring-fence increases somewhat the systemic risk and decreases the ability of banks to withstand the risk and has significant costs."
Intensive lobbying of the coalition in the run-up to Sir John's final report, published in September, eventually led to a recommendation that the split be delayed until 2019 – close to the end of the next parliament.
Its final conclusions called for banks to maintain up to 20% of their assets to help absorb any future losses.
Ten per cent of this would be held in capital, with the remainder in 'bail-in bonds', and make it easier for customers to switch their current accounts.
Chancellor George Osborne said in September: "This commission has tackled that big question that we face in Britain, which is how can we be a home to successful banks that compete around the world, but lend to British families and British businesses, but at the same time protecting us as taxpayers from the cost of them going wrong, and not ending up with a multi-billion pound bill when the bank collapses."
He will reveal the government's plans in details tomorrow with a Commons statement at 15:30 GMT, which is expected to be accompanied by a white paper on the issue.
Mr Cable added: "We can't have a position where the big banks are too big to fail, where there is a taxpayer subsidy."