He acknowledged the markets meltdown was a worldwide problem and that his meeting with the G7 finance ministers today was vital.

"The world is sending an unmistakable signal: We're in this together and we will come through this together," he said.

"The US government is acting, we will continue to act to resolve this crisis.

"The Federal Government has a comprehensive strategy. We can solve this crisis and we will."

Mr Bush argued that high anxiety among both investors and the general public about the economy was making the credit crisis more severe.

He said the government's financial rescue plan was aggressive enough and big enough to work, but would take time to fully kick in.

"We are a prosperous nation with immense resources and a wide range of tools at our disposal ... We can solve this crisis and we will," he said in the short speech from the White House.

He spoke as leaders of the world's leading economies gathered in Washington amid frozen credit markets, panic selling in stock markets and a looming global recession.

Mr Bush said he understood how Americans could be concerned about their economic future, "that anxiety can feed anxiety and that can make it hard to see all that's being done to solve the problem."

Mr Bush was speaking just an hour after US stocks plummeted on Wall Street. The Dow Jones industrials average of blue chip firms sank more than 500 points in the first five minutes of trading before recovering slightly.

"The plan we are executing is aggressive," Mr Bush said.

"It is the right plan. It will take time to have its full impact. It is flexible enough to adapt as the situation changes. And it is big enough to work."

He went on: "This is an anxious time, but the American people can be confident in our economic future. We know what the problems are, we have the tools we need to fix them, and we're working swiftly to do so."

Meanwhile, Eurozone countries will hold an urgent summit meeting on Sunday to discuss ways to respond to the worldwide financial crisis.

French President Nicolas Sarkozy's office said national leaders are to join European Union Commission President Jose Manuel Barroso and European Central Bank chief Jean-Claude Trichet for the meeting in Paris.

Mr Sarkozy's office said in a statement that it aims to define "a joint action plan" among the 15 countries using the euro currency and the ECB. France called the meeting as current holder of the EU presidency.