Alistair Darling, the Chancellor of the Exchequer, came under increasing pressure to recapitalise the UK banks by taking a government share in the banking system in the Commons yesterday.

In a statement to MPs on the global financial crisis after their summer break, the Chancellor gave little away but said that he would do "whatever is necessary" including re-capitalising the banks - effectively part nationalisation - to maintain stability.

Mindful of volatility in falling international stock markets, Mr Darling delivered a calm message to the Commons but his statement did little to stop share prices crashing in London.

Former Tory chancellor Ken Clarke was among those who called on Mr Darling to send a clear and strong message to the markets and to customers worried about their deposits.

He asked: "Is it right to assume that the government now accepts that the Treasury must support the Bank (of England) in providing just as much liquidity as is necessary on widest possible security of assets, class of assets as security, and for as long as is necessary until the money markets start to function again and until inter-bank lending is resumed?"

Mr Darling said speculation could be harmful, and added: "It is important, when we have proposals to make in whatever aspect we are covering, whether it is liquidity, regulation, capital, whatever, that we make those as soon as possible, consistent, of course, with having proposals that are fully developed and ready to be implemented."

The SNP's Stewart Hosie said: "Can I ask you as a matter of urgency to finalise the plan you have and make a firm, detailed, comprehensive statement on the actions government intends to do? Otherwise the government will be seen to be buffeted by events, acting only in a reactive manner."

Mr Darling responded, as he did to other questions, by setting out what the government had done so far, including injecting £40m into financial markets this week.

"There are further things we need to do and I will come to the House as soon as I am ready to do so," he said.

Mr Darling and the Opposition are keen to avoid a repeat of the American situation where a rescue plan for banks ran into the political quicksand, making matters worse.

Shadow Chancellor George Osborne reaffirmed the Tories' commitment to work with the government to get banking reforms on the statute books and led calls for re-capitalisation.

Mr Osborne said: "Would it not be irresponsible to not even at least consider more dramatic measures to help our banks, including support from creditors and government injection of capital?

"Of course there would have to be very strict conditions to protect taxpayers and ensure that they benefit first from any gains. We couldn't contemplate taxpayers' money being used to prop up the kind of salaries and bonuses we have seen in recent years.

LibDem Treasury spokesman Vince Cable also called for a government-backed recapitalisation programme, a form of "partial nationalisation".

He said: "It is appropriate in emergency conditions to make it absolutely clear that the mandate of the Bank of England must include responsibility for averting a meltdown in the financial and economic system."

Mr Darling said the Financial Services Authority's extension of deposit protection would cover 98% of UK bank accounts and that the Bank of England's independence was sacrosanct.

Mr Darling made implicit criticism of the action by the Irish and German governments to guarantee deposits but stuck to his "ready to do whatever is necessary" script.