Stock markets plummeted still lower on Wall Street and around the world Friday despite all efforts to slow the selling stampede. The globe's industrial powers urgently debated even more forceful actions to prevent a worldwide economic catastrophe.

On Wall Street, the Dow Jones industrials ended down nearly 20 percent in the past week. Friday, the Dow dropped nearly 700 points more in the opening minutes, recovered briefly and then turned sharply lower again. The Dow recovered most of those losses to close down 128 points on the day.

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In Washington, Treasury Secretary Henry Paulson and Federal Reserve Chairman Ben Bernanke met with their counterparts from the world's six other richest countries as a rout of financial markets showed no sign of letting up in the face of dramatic rescue efforts in the U.S. and abroad.

Stock prices hurtled downward in the United States, Europe and Asia, even as President Bush tried to reassure Americans and the world that the U.S. and other governments were aggressively addressing what has become a near panic.

"We're in this together and we'll come through this together," Bush declared at the White House as finance ministers and central bankers from the world's seven richest nations gathered nearby. "Anxiety can feed anxiety, and that can make it hard to see all that's being done to solve the problem."

Foreign stock markets also fell sharply. Great Britain's FTSE index ended below the 4,000 level for the first time in five years; Germany's DAX fell 7 percent and France's CAC-40 finished down 7.7 percent. Japan's benchmark Nikkei 225 index fell 9.6 percent, also hitting a five-year low. For the week, the Nikkei lost nearly a quarter of its value. Russia's market never even opened.

Bush made it clear the United States must work with other countries to battle the worst financial crisis that has jolted the world economy in more than a half-century.

"We've seen that problems in the financial system are not isolated to the United States," he said. "So we're working closely with partners around the world to ensure that our actions are coordinated and effective."

Fear has tightened its grip on investors worldwide even as the United States and other countries have taken a series of radical actions including an unprecedented, coordinated interest rate cuts by the Federal Reserve and other major central banks.

Besides the United States, the other members of the G7 -- the Group of Seven -- meeting in Washington are Japan, Germany, Britain, France, Italy and Canada. Finance officials also planned to meet with Bush Saturday at the White House.

"We are in a development where the downward spiral is picking up speed," said Germany's Finance Minister Peer Steinbrueck, who wants to see an orchestrated response among the G7.

So does French Finance Minister Christine Lagarde, who said a "coordinated, synchronized and rightly timed approach" was needed.

An even larger group of nations -- called the G20 -- will meet with Paulson on Saturday evening. How the world's finance officials and central bank presidents can better contain the spreading financial crisis also will dominate discussions at the weekend meetings of the 185-nation International Monetary Fund and the World Bank in Washington.

"Addressing these challenges requires the dramatic steps we are taking here in the United States and it requires strong international partnerships," Paulson said this week. "We must also take care to ensure that our actions are closely coordinated and communicated so that the action of one country does not come at the expense of others or the stability of the system as a whole."

Dominique Strauss-Kahn, head of the IMF, which is the world's financial firefighter, urged countries to work together to come up with coordinated plans to make sure that squeezed banks and other financial institutions have access to both quick and longer-term sources of cash to help them weather the financial storm. He also said countries should work together to make sure that bank depositors are adequately protected.

"These actions should help to restore trust and confidence in financial markets," he said.

The British, who recently announced a plan to guarantee billions of dollar worth of debt held by major banks, are pitching that idea to the rest of the G7 members.

"What we have said is that any proposal that's put forward by one of our global partners, we will take a look at it, we will review it," said White House press secretary Dana Perino.

Separately, the United States is exploring ways the government might inject billions into banks in exchange for ownership stakes. Earlier in the week, Britain moved to pour cash into its troubled banks in exchange for stakes in them -- a partial nationalization.

The idea behind these ideas -- as well as bold steps previously announced in recent weeks -- is to get credit flowing more freely again.

In the United States, hard-pressed banks and investment firms are drawing emergency loans from the Federal Reserve because they can't get money elsewhere. Skittish investors have cut them off, moving their money into safer Treasury securities. Financial institutions are hoarding whatever cash they have, rather than lending it to each other or customers.

The lending lockup -- which is making it harder and more expensive for businesses and ordinary people to borrow money -- is threatening to push the United States and the world economy as a whole into a deep and painful recession.

In Europe, governments have moved to protect nervous bank depositors. Germany pledged to guarantee all private bank savings and CDs in the country, and Iceland and Denmark followed suit. Ireland went even further by also guaranteeing Irish banks' debts. The United States will temporarily boost deposit insurance from $100,000 to $250,000 in cases where its banks or savings and loans fail.

Some economists have suggested the United States move to temporarily cover all deposits.

Asked whether that was something the Bush administration was considering, Perino said: "All of those things are questions that the policymakers can take up and think about, discuss and then once we have -- if we have -- a decision about moving forward on any of those issues, it will either come out of the Treasury Department or we'll keep you updated."

The Fed, meanwhile, has repeatedly tapped its Depression-era authority to be a lender of last resort, not only to financial institutions but also to other types of companies. Earlier this week, the Fed said it would buy massive amounts of companies' debts, in another unprecedented effort to break through the credit clog.

Not everyone favors such drastic actions. Critics worry that the Fed and the Bush administration are putting billions of taxpayers' dollars at risk.