Chancellor Alistair Darling is set to announce details of a £50bn rescue package for the UK banking system.
The UK government has announced details of a rescue package for the banking system worth at least £50bn.
Details of the scheme, expected to be unveiled at 0700 BST, will include a proposal to use taxpayers' money to take stakes in major banks.
It will make extra capital available to eight of the UK's largest banks and building societies.
The initiative is aimed at stabilising the financial system by giving banks - who usually rely on world money markets - greater access to cash.
In return for the funding, the government will receive preference shares in those institutions.
The measures will come a day after some UK banks saw steep share price falls.
A further £200bn will be made available by the Bank of England for short-term borrowing to provide liquidity to banks and building societies.
HBOS lost 42% of its value while Royal Bank of Scotland slipped 39%.
The banks that have confirmed they will take part in the scheme are Abbey, Barclays, HBOS, HSBC, Lloyds TSB, Nationwide Building Society, Royal Bank of Scotland and Standard Chartered.
However the FTSE 100 index rallied as word of the proposals began to emerge.
The Treasury said that other banks would be able to apply for inclusion in the plan.
It matters to all of us that the ambitious plan works - not least because the reluctance of our banks to lend to companies and households is sending the economy into recession Robert Peston, BBC business editor Read Robert's blog
Prime Minister Gordon Brown is expected to call the proposed rescue package a "bold and far-reaching" solution, which will go "to the heart of the problem".
"Extraordinary times call for bold and far reaching solutions," he is due to say.
"This is not a time for conventional thinking or outdated dogma but for fresh and innovative intervention that gets to the heart of the problem."
'Turbulent market'
BBC business editor Robert Peston - who revealed that the government was to invest in banks, effectively semi-nationalising them - said there was hope from some that the move would "bring a bit of calm to the extraordinarily turbulent banking market".
With a £50bn rescue package the equivalent of £2,000 per taxpayer, the decision was a "big moment" for the Prime Minster, he added.
"This is the first genuine, full-scale economic crisis he has had to face since he entered government, as chancellor of the exchequer, in 1997.
"His place in history will depend on whether taxpayers' cash is being used to slow or stem the downward spiral in the economy or whether this is good money disappearing down a deep black hole."
Confidence collapse
The government is expected to take "preferred shares" in leading banks.
These would not give it voting rights in the running of the institutions and observers say the government is unlikely to interfere in the day-to-day operations of the business.
The investment is intended to make banks stronger and more confident to lend.
There has been a collapse of confidence in money markets - with banks being increasingly nervous to lend to one another over fears they may not get their money back.
The government intervention will be designed to try and ensure that big banks have enough cash to fund day-to-day operations.
"We need a full and comprehensive plan. We don't need any more step-by-step measures," said Peter Hahn, a banking expert at the Cass Business School.
"Markets should react positively but we need to know what the details are."
