Athens, Greece ? The Greek government teetered and stock markets around the world plummeted Tuesday after a hard-won European plan to save the Greek economy was suddenly thrown into doubt by the prospect of a public vote.

One day after Prime Minister George Papandreou stunned Europe by calling for a referendum, the ripples reached from Athens, where some of his own lawmakers rebelled against him, to Wall Street, where the Dow Jones industrial average plunged almost 300 points.

Papandreou convened his ministers Tuesday night, and a spokesman said the prime minister was sticking to his decision to hold the referendum, which would be the first since Greeks voted to abolish the monarchy in 1974. Papandreou has also called a vote of confidence in his government, to be held midnight Friday.

“The government is not falling,” said Angelos Tolkas, a deputy government spokesman.

Under a recently amended law, a referendum can be called by presidential decree on issues of grave national concern, if it is proposed by the cabinet and approved by absolute majority in the 300-member parliament.

With several of his lawmakers rebelling, it was unclear whether Papandreou would have enough support to push the idea through. Although he had not set a specific question or date for the referendum, ministers indicated it would likely be held in January.

Papandreou’s decision upended a deal that was the product of months of work by European leaders who were trying, sometimes opposed by their own people, to agree the details of a second bailout for Greece and shore up their own economies in the name of saving the euro, the common currency.

The deal would require banks that hold Greek government bonds to accept 50 percent losses and provide Greece with about $140 billion in rescue loans from European nations and the International Monetary Fund.

But Greeks have been outraged by repeated rounds of tax increases and salary and pension cuts imposed as the government struggles to meet the conditions of a first, $153 billion bailout the country has been relying on since May 2010. With Greece facing a fourth year of recession next year, unions have held frequent strikes, and protests have often degenerated into riots.

A Greek rejection of the second rescue package could cause bank failures in Europe and perhaps a new recession in Europe, the market for 20 percent of American exports. It could also cause Greece to leave the alliance of 17 nations that use the euro.

European leaders made no secret of their displeasure.

“This announcement surprised all of Europe,” said a clearly annoyed French President Nicolas Sarkozy, who has been scrambling to save face for Europe before he hosts leaders of the Group of 20 major world economies later this week.

“Giving the people a say is always legitimate, but the solidarity of all countries of the eurozone cannot work unless each one consents to the necessary efforts,” he said.