The Polish government is postponing a major reform to decentralize Poland's economy and introduce worker control, originally scheduled to go into effect Jan. 1.

The delay is officially attributed to lack of preparation and concern that the country's desperately weak economy could not now sustain the shock of adjusting to a new system. But leaders of the independent Solidarity trade union federation sharply protested the postponement and provisional measures decreed by the government as a step backward.

In place of the rapid decentralization of control that had been promised, the Warsaw government last week issued interim measures, intended to last a year or more, to deal with Poland's severe shortages by empowering regional agencies to buy essential resources and allocate them to key industries.

Solidarity union leaders criticized the action as a step back toward more centralized control of the economy, and as an attempt by communist authorities to cancel laws, passed less than three months ago, which conferred more independence on individual factories and provided for worker self-management.

"The so-called provisional system for 1982," declared the union, "in practice retains the old system of economic management at the same time putting the material burden of decisions -- which will remain in the hands of central organizations -- on the enterprises and their crews. That is tantamount to cancellation of the reform and the bills on the enterprise and self-management adopted by the parliament."

The statement was contained in the Solidarity communique issued in Radom last week, where the union's leadership also threatened a general strike over the government's proposed emergency powers act. Solidarity's suspicions about the government's commitment to genuine economic reform have fed the latest downturn in relations between the national worker organization and Communist Party and state authorities.

The union's strike threats, which followed the storming Wednesday by Polish police and Army troops of a Warsaw fire fighter's academy to remove striking cadets, were matched yesterday by a warning from Stefan Olszowski, a hard-line member of the ruling Politburo, to be mindful of the government's new determination to use force to maintain order.

But tonight, the Politburo issued a remarkably conciliatory statement saying Solidarity's fears about the emergency powers legislation were unfounded and stressed in particular that the proposed bill, which has yet to be published, contains no ban on freedom of movement and assembly.

The Politburo repeated the party's offer, so far rejected by Solidarity, to start a front of national unity with Solidarity and other groups. "Only together can we lead Poland out of the crisis," the statement said, "so nobody has the right to make this process difficult."

The dispute over the introduction of the economic reform reflects the vicious circle Poland has fallen into trying to mount an economic recovery while protecting the political freedoms won during the past 15 months of social upheaval here.

On the one hand, a thorough liberalization of the traditional central planning system that has run Poland into confusion, corruption and huge debts is considered essential -- and not only for the country's economic health. An independent self-governing economy is seen by the union as a condition for cementing democratic political gains.

On the other hand, the intended reforms, which are similar to those undertaken earlier by Yugoslavia and Hungary, are bound to be traumatic when instituted, and it is doubtful the Polish economy at the moment could withstand the additional disruption.

This dilemma was summarized in a recent article in the leading Polish weekly Polityka.

"Now it appears that on Jan. 1, our economy will not be shaken to its foundation," wrote journalist Danuta Zagrodzka. "Our society and the economy itself would not sustain such a shake of the market. However, will they be able to make even one step forward without it?"

While some of even the most ardent reformers concede that the time may not be right to introduce many of the changes envisioned, what has angered Solidarity is the way the government has managed the postponement and the direction the bridging measures seem to be pointing.

Unlike the legislation approved by parliament in September, the new measures were not presented for public consideration but were simply decreed by the Council of Ministers. Solidarity representatives were briefed on the measure just three days before the decree was approved on Nov. 30.

Government officials say they had to act quickly in order to have rules in place by Jan. 1. Responding to criticism, Wladyslaw Baka, the minister in charge of the economic reform, denied in a television interview last night that the provisional system was an attempt to stall the reform process.

Baka said that if the country's economic controls were relaxed now and new powers ceded to individual enterprises, many factories would go bankrupt and there would be a surge in unemployment.

The poor economic picture, however, appears to be reinforcing the hand of hard-line elements in the party and state apparatus opposed to the reform.

The key to the reform is that factories, which have been heavily subsidized and programmed by state-run corporations, were to become self-financing. In addition, self-managed workers' councils, elected by secret ballot, were to take over a major role in making broad decisions about production, pricing, investment and so on -- operating somewhat like a board of directors in a Western factory.

Passage of the basic reform bills in September was supposed to be followed by enactment of implementing legislation covering financing, tax and other details of the reform. But this has not happened.

Further, the workers' councils are developing more slowly than expected. Solidarity reported last week that only 10 to 20 percent of the factories in large regions had formed workers' councils and the movement appeared even weaker in smaller regions.

Most significantly, Poland's economic situation remains shaky, hampered by work stoppages and shortages of nearly everything. The statistical office last month reported a 15 percent drop in industrial production over the year before.

"Unfortunately, the situation became complicated during the past year," said Jozef Kaleta, director of the economic academy of Wroclaw, in a recent interview with a Polish magazine. "A year ago, it would have been much easier to launch the reforms."