British Prime Minister Gordon Brown and Chancellor Alistair Darling are to meet the Governor of the Bank of England and the Chairman of the Financial Services Authority in Downing Street at 5pm, the Prime Minister's spokesman said.
The meeting will consider the government's plan to stabilise the financial system and proposals for long-term reform, the spokesman said.
Mr Darling, Mr King and Lord Turner will initially meet as the tripartite committee responsible for maintaining financial stability before being joined by Mr Brown.
Earlier, the Prime Minister briefed the weekly meeting of the British cabinet on the latest developments just as the Royal Bank of Scotland became the latest victim of the fear and uncertainty gripping financial markets.
At one point, shares in RBS dropped 40% following a report that its chief executive, Sir Fred Goodwin, had met Mr Darling last night – with the bosses of Barclays and Lloyds TSB – to discuss an injection of government cash.
RBS was forced to issue a statement insisting it had not made any request for government capital.
Downing Street made clear its irritation at the way details of the meeting had apparently leaked out.
"The government is certainly not going to engage in irresponsible briefing," Mr Brown's spokesman said.
There is widespread speculation that the Government is preparing to bolster the banks' balance sheets by taking shares in them – effectively a part-nationalisation.