"We will continue to welcome investing companies with a clear strategy and vision to the market," he said. "But given the number of inactive investing companies on the market, and the potential for new investing companies without institutional backing to be more susceptible to price speculation, we felt the rules should be changed."The most actively traded of yesterday's flotations was India Star Energy, which raised £900,000 and whose shares rose from a placing price of 1p to 2.37p. The companies are usually chaired by a serial entrepreneur with the backing of a small coterie of usually private individuals.Mat Wootton, the deputy head of AIM, said the Exchange had anticipated a rush to beat the deadline, but said the crackdown would be in the long-term interests of the market. An additional five shells are expected to float today, which will take the total to 16 in just three days. The Exchange says it is worried that too many cash shells are giving AIM a reputation for encouraging highly speculative ventures and undermining its status as a market for growth companies.The companies floating yesterday were promising to make investments or acquisitions in fields as diverse as retail, mining, financial services, security guarding, nanotechnology and oil exploration. But MPs were concerned that away from bank branches, the number of charging ATMs was growing, penalising people on low incomes.The Post Office was singled out for special attention, as 95 per cent of people live within a mile of a branch Mr McFall said: "It's a huge reach.

But the Post Office is out of sync with the practice of other financial institutions where banks and building societies have free machines on their sites to avoid long queues [for free over-the-counter services]. It's not helping financial inclusion."He also urged HSBC, Royal Bank of Scotland and HBOS to allow their current account customers to withdraw cash over post office counters. Customers of only nine banks, such as Barclays and LloydsTSB, are able to do so at present.The Post Office said the 34 million free cash withdrawals a month at its branches dwarfed the 2 per cent of transactions made at charging ATMs, and stressed it did not make profit from the charging machines.The committee said competition between operators should ensure there is no need for a cap on charges, provided there are enough free machines and that charging machines are labelled clearly.. Nine "cash shells" listed on the junior AIM market yesterday, as brokers rushed to avoid a crackdown on the flotation of companies with no operating business. The London Stock Exchange is imposing a minimum funding requirement for shells and from this Friday they must raise more than £3m to qualify for admission to AIM. At post offices, more than 75 per cent of machines installed charge up to £1.50 for a withdrawal, costing consumers about £10m a year.The committee, chaired by John McFall, voiced concern over the growth of charging machines, which account for 37 per cent of all ATMs (automatic teller machines) in Britain.

MPs said the sale of 816 free machines by the banking group HBOS to the private operator Cardpoint was a "noteworthy development", raising fears other banks could do the same.The committee welcomed commitments from major banks that they will not introduce charges for machines. The company said its performance during the crucial month of January had been disappointing, and so it would not meet the City's earnings forecasts. It also warned that the outlook for February and March "remains uncertain". In November, the company halved its dividend.Whitehead's shares closed down 1.15p at 43p yesterday..