Ireland's shares fell again tonight as its directors were locked in crisis talks about the future of their embattled bank with a possible break up or outright sale on the cards.

Meetings started last night amid a continuing wipeout of the share price, which has accelerated despite chief executive Vikram Pandit's announcement on Monday of 52,000 job cuts.

Today's meeting will consider "all options", including selling the firm or merging with rivals. Analysts said there was no obvious buyer for the vast business given the crisis ripping through global markets.

Citigroup became the world's biggest financial services company through an aggression expansion programme. But now its very size and geographic spread is proving its weakness as the credit crisis goes global.

Investors were horrified last week when the group's share price fell below $10 for the first time, but since then it has slumped by more than 50%, closed yesterday at $4.71 and slid below $4 as Wall Street opened this afternoon.

The slide has placed huge pressure on the bank, which employs thousands of people at its Canary Wharf headquarters.

Even an endorsement yesterday from billionaire Saudi investor Prince Al-Waleed bin Talal who said he would up his stake in the bank, made no impact on the share price. The Prince said he would increase his holding from 4% to 5%, claiming the shares were "dramatically undervalued".

Citi executives said the emergency talks were in their initial phase and about exploring options open to them.

They have started exploring the possibility of selling off parts of the firm, including the Smith Barney retail brokerage, the global credit card division and the transaction services unit, which is one of Citigroup's most lucrative and fast-growing businesses.

It has also asked the US Securities and Exchange Commission to reinstate a ban on the short-selling of financial stocks in an attempt to arrest their downward spiral of its share price.

US Treasury Secretary Hank Paulson, while defending his actions in the face of the financial crisis, refused to say whether there would be any government help for Citi.

Speaking in California, Paulson said he would not comment on individual cases.

Pandit and other Citigroup executives say they are frustrated and by this week's 50% stock decline and do not understand why investors have deserted the bank.

However, the latest run on Citi shares began after Paulson's decision last week not to buy troubled assets from banks as he had originally planned. Citigroup's balance sheet includes many of the toxic securities and loans that helped to create the crisis and many investors had hoped they would be offloaded onto the government.

Even with all options on the table, Citi may find little room to manoeuvre when it comes to a sale or merger as few of the most likely buyers are in financial shape to act.

Pandit's old firm Morgan Stanley, once considered a buyer, is understood to be no longer interested.

Morgan and Citigroup held preliminary discussions about a merger in September with Morgan attracted by access to the bank deposits.

Goldman Sachs would also be interested in those but is hamstrung by its own problems.

While it may covet parts of the Citigroup, empire an outright buy is likely to be beyond its current resources.