FRANKFURT, Germany — Soaring demand for euro notes and coins is forcing many European commercial banks to order up more cash and producing at least modest shortages of cash at stores and banks.
Cash withdrawals from banks have been three to four times normal this week, far higher than bankers had expected. But people have not been spending their new money nearly as fast as they are acquiring it, which is leading to imbalances.
"It is a problem," said Peter Hageman, a spokesman for the Belgian Federation of Wholesalers and Retailers. "Consumers are going to shops to spill their last Belgian francs, and the euros that have been front-loaded are diminishing."
Citing unexpectedly high demand, the European Central Bank injected additional money into the banking system on Friday by offering 25 billion euros in three-day loans to commercial banks.
The move will not ease any immediate cash shortages this weekend, but it will shore up cash supplies that have been hit hard by the heavy withdrawals.
"Overall, the supply of money is there," said Antti Heinonen, the European Central Bank's official in charge of the currency changeover. But, he added, "some banks have not reserved enough money and they are now having difficulty in meeting the needs of retailers."
European Commission officials predicted that Saturday would be a big challenge, because it is a busy shopping day in many countries. Though large retailers insist that they are prepared with a good supply of euro cash, smaller stores and businesses already have put up signs warning customers not to pay for very small purchases with very large bills in the old currency.
Rene de Wit, chief financial officer at the Belgian supermarket chain Colruyt, said his stores still had plenty of cash. But the company is refusing to accept 10,000 Belgian-franc notes, which are worth about $250, unless a person is buying more than 3,000 francs worth of merchandise.
In the Netherlands, Dutch banks planned to extend their bank hours on Saturday so businesses had more chance to restock their tills.
The president of France's central bank, Jean-Claude Trichet, implored banks on Friday to let people, including noncustomers, change their French francs to euros at no cost.
But he also asked shoppers not to burden retailers by using the largest denomination franc notes and to make more use of checks and credit cards.
Many banks have been caught by surprise by the large number of customers who decided to convert their francs, marks, pesetas and lire at banks rather than simply spending them at stores over the next few months.
Here in Frankfurt, many bank branches have been mobbed with customers ever since the currency made its debut.
The worst congestion was on Wednesday, the first day banks were open after New Year's Day, when many people waited for more than an hour and several branches briefly closed their doors to keep the crowds down.
But the lobbies of many banks were packed on Friday. At Citibank's branch in the heart of downtown Frankfurt's shopping area, the bank told tourists that it would only change foreign currencies to euros for its own customers.
At SEB Bank's Frankfurt's branch, which was also mobbed, signs warned people that the bank would not convert marks to euros for people who were not its customers. "It is for technical reasons," said a woman at the information window. "We are only changing money by booking it into a person's account and then withdrawing it in euros from their account."
If cash shortages do arise, they should have limited consequences. Shops that run out of euros, or particular denominations of euros, can still give change in the old currencies. National central banks heavily discourage the practice, but it is not illegal.
The imbalances should correct themselves eventually, as customers pay for more purchases in euros and thus replenish cashiers' tills, bankers say.
There was some evidence on Friday that the process might be starting. The European Commission estimated that 40 percent of cash transactions in the 12-nation euro-zone were entirely in euros. In the Netherlands, which has been the fastest at converting, the Dutch central bank estimates that 80 percent of purchases are in euros.
European officials estimate that more than half of cash transactions are now entirely in euros in Germany, Greece and Luxembourg. In Belgium, France, Italy and Austria, they say, the share is about 25 percent.
As the holiday week came to an end on Friday, the changeover continued to proceed smoothly in most countries. But there were some new glitches. Counterfeit euros showed up in Ireland and the Netherlands, though the police described the evidence as amateurish and easily detectable.
The Finnish central bank reported that it had found real but defective 500-euro notes. Though authentic, the notes were missing one of the holograms placed on the bills to protect against counterfeiting.