From their inception two years ago, Poland's reconstituted trade unions, which the government hopes will replace the outlawed Solidarity movement, have been haunted by their identification in the minds of many Poles with the communist-controlled unions of pre-Solidarity days.

So it did not do much for their image when, hunting recently for office space in the capital's tight real estate market, the unions' new coordinating alliance set up headquarters in the same gray stone structure on Copernicus Street that once housed the old Central Council of Trade Unions, discredited by the labor upheaval of 1980.

"Speaking frankly, we're not afraid of ghosts," alliance spokesman Franciszek Ciemny said the other day, trying to shrug off the awkward connection with the past.

With purposeful regularity, Poland's official press has been reporting a steady rise in union membership in the face of continued calls by the Solidarity underground to boycott the communist party-sponsored organizations.

For a brief spell this month, the unions even appeared to be flexing some muscle, rejecting government proposals for food and energy price increases. At first, the government seemed to back down, promising to reconsider the increases in light of union pressure. The retreat boosted the unions' image and credibility -- but only for a short while, as things turned out.

In the end, the government decided to stagger the price increases instead of concentrating them in March as originally planned. But the increases will be spread over only a few months, not over a longer period as the unions had expected. Many Poles, including the union chiefs, said they felt deceived by the government's tactics.

Yet the most the labor bosses could do at a meeting they demanded last week with the Polish leader, Gen. Wojciech Jaruzelski, was complain and warn authorities not to raise prices in such a manner again.

Why the government acted in a way that left its own fledgling unions angry and looking impotent puzzled many Poles and western diplomats.

"We were surprised by the government's decision," said Leszek Brojanowski, head of the federation of printers' unions and one of eight deputy chairmen of the central alliance of union federations. "It was a blow to our credibility. We've been noting a stable rise in membership. We're worried about how such actions may affect our growth."

The unions now claim about 5 million members, half the number that belonged to Solidarity before the imposition of martial law in December 1981 ended the Soviet Bloc's first independent trade union. In October 1982, the communist-controlled parliament dissolved Solidarity and established the new trade unions.

In contrast to Solidarity, which owed its power to strong regional structures, the new unions were divided along craft lines. On paper, they did appear to differ somewhat from the unions that had existed before Solidarity. Before, each factory union derived legal standing from a Central Council of Trade Unions. Now, each union carries its own legal status. The law declares individual unions to be self-managed and independent, which theoretically gives union cells greater freedom.

By last year, however, the factory unions were busily pyramiding themselves into large branch federations and, in November, the federations formed a central alliance, all of which looks to many Poles like the same hierarchical structure that the old, heavily bureaucratized unions had.

The law grants the new unions the right to strike and allows "other forms of protest, provided law and order and the principles of social coexistence are not disturbed." But strikes may be declared only after a long, complex adjudication, and political strikes are specifically banned.

A strike alert was called last November over a pay dispute by a union at the Glogow steelworks near Wroclaw in southwestern Poland. But management never took the warning seriously, and no walkout occurred. In February, the federation of metallurgical unions, which is among the most militant of the new labor groups, threatened "legal protests," possibly in the form of mass meetings and demonstrations, against the planned price increases. But government censors barred publication of the federation's announcement.

Whatever their real level of independence, the official unions cannot escape their association with the communist party, which conceived them and frequently is seen as directing them.

The party was initially hesitant about instructing its members to join the labor groups, lest it appear to be dominating them. But by mid-1983, party cells in factories were ordering loyalists to sign up.

Communists now hold top posts -- among them, the chairmanship of the alliance of union federations, held by Alfred Miodowicz, a blast furnace operator from the Lenin steelworks near Krakow.

Solidarity activists say communist authorities have put pressure on some workers to enlist in the unions and enticed others to join by offering promotions, access to factory-owned vacation facilities, reduced rates for merchandise and the chance to buy scarce goods. Last year, for instance, a union at the Stomil tire factory in Olsztyn caused a furor by obtaining extra tea and coffee and selling the hard-to-get items only to union members.

The government admits it is having an especially difficult time attracting young workers to the unions. Membership among that age group ranges only between 10 and 20 percent of those eligible.

To help the unions recover from their humiliation over price increases, the government has agreed to sit down with them on a joint committee and take a broad look at inflation.

On another committee, state officials expect some hard negotiating with union representatives over a general framework for collective bargaining agreements. The government wants to streamline wage arrangements by eliminating special benefits now provided some workers. Miners, for instance, get extra coal and railway workers travel by train at a discount. The unions insist that the perks stay.

But for many Poles these economic questions remain secondary to the political wish to be allowed to set up alternative unions. Under the 1982 trade union act, only one union is permitted per factory. This rule expires at the end of this year, and Solidarity supporters have been hoping then to begin carrying out their slogan of "union pluralism."

But communist authorities have hinted broadly that they do not intend to let competitive unions spring up. Even Miodowicz, the union alliance chairman, has opposed a pluralistic labor union structure, contending that alternative unions would divide the work force, bring conflict among workers and lead to a costly bidding contest for members that would divert attention from more urgent national economic concerns.