Workers across the country walked off their jobs, and union leaders led a mass rally in front of the government palace here today in the strongest show of opposition yet against the economic policies of President Raul Alfonsin.

In the culmination of a month-long "battle plan" by the opposition General Confederation of Labor, Buenos Aires workers struck this morning, and general strikes ranging from 12 to 24 hours were called in most major provincial cities.

This afternoon, tens of thousands of people called by the labor federation and opposition political parties gathered in the central Plaza de Mayo and cheered as union spokesmen called on the government to raise salaries, increase production and abandon austerity measures meant to stabilize Argentina's crisis-stricken economy. Argentine news services reported the size of the crowd at more than 100,000.

The mobilization was the largest ever organized against Alfonsin's 18-month-old democratic government and signaled growing resistance to the president's efforts to cut spending in an effort to control surging inflation and to negotiate new agreements on the foreign debt with banks and the International Monetary Fund.

"The national economy is subordinated to the IMF, there is no reactivating plan of production, and this policy will lead us to social chaos," said a statement by the labor federation, whose leadership is dominated by members of the populist Peronist movement.

"Democracy with hunger is not democracy," added the confederation's leader, Saul Ubaldini, in a speech at the rally. If authorities "are not capable of rectifying the economic policy," he warned, "let them leave."

Alfonsin's Radical Party government called the strike "political and destabilizing" and adopted several strong measures to dissuade workers from participating. Those state workers banned from striking were told they would be disciplined if they left work, and officials warned that they might take action against some unions if they found the strike had not been called legally.

Alfonsin bitterly criticized Ubaldini last week as a "crybaby" and a "sissy."

Although the attacks represented an escalation of government efforts to check its labor opposition, today's stoppage and rally appeared larger and more effective in the capital than the national strike called by the federation last September.

Traffic thinned to a trickle on Buenos Aires streets this afternoon and many stores closed as columns of protesters organized by unions and leftist political parties marched toward the government palace. The large cities of Cordoba, Mendoza and Tucuman were also largely paralyzed by the strike, although walkouts were less noticeable in other interior centers, according to news service reports.

As in September, the unions launched their offensive at a time when the government is facing a dangerous surge of inflation even as it seeks to negotiate a new economic package with the IMF. After lessening briefly late last year, monthly inflation reached 29.5 percent in April, surpassing the previous high under Alfonsin's government of 27 percent last September. If inflation were to continue at the April rate, it would reach an annual rate of 2,100 percent.

In a speech to a massive rally of government supporters last month, Alfonsin promised a "war economy" of austerity measures. Government officials have announced plans to cut their budget for this year by 12 percent, eliminate 20,000 to 30,000 state jobs, and sharply raise taxes and utility rates.

Even as the demonstrators shouted slogans against the IMF at today's opposition rally, government economic officials left for the United States for a new round of negotiations with the agency on an economic agreement allowing the refinancing of Argentina's $45 billion foreign debt. The IMF suspended its last agreement with Argentina in March after the government failed to meet inflation-related targets.