Tentative signs are emerging that Poland's leadership, faced with dismal economic projections and the prospect of limited help from its East Bloc allies, is debating whether to loosen its martial-law grip in order to regain Western economic assistance.

The official Communist Party line is that Poland will not bow to "economic blackmail." Spokesmen for the martial-law authorities have insisted that Western sanctions imposed following December's military crackdown have served only to increase Poland's dependence on the Soviet Bloc.

But this display of bravado has been undercut by an article in the latest edition of the influential political weekly Polityka predicting "economic disaster" unless Poland can find the money to pay for essential imports. The author, Dr. Andrzej Olechowski, suggests that since the Soviet Bloc already faces so many economic problems of its own, the bulk of the funds must come from the West.

After presenting a series of devastating statistics on the likely fall in national income this year--for the fourth successive year--Olechowski comes to the conclusion that Poland will have no alternative but to take steps to ease the Western credit freeze.

In a passage directly at odds with official government policy, he adds, "These steps should include external and internal political measures which would lead to national reconciliation and remove the basis for the imposition of sanctions--or at least differentiate the approach of Western countries on this issue."

In addition to the trade sanctions announced by the Reagan administration, many Western governments have refused to consider Poland's appeals for fresh financial credits unless martial law is lifted, thousands of detainees released and negotiations resumed with the independent Solidarity trade union and the Roman Catholic Church.

It is difficult to judge to what extent Olechowski, who heads the economic forecasting department at the Institute for the Study of Economic Trends and Prices in Warsaw, is speaking for others within the Polish establishment in calling for political concessions. At a press conference Wednesday, senior Foreign Trade Ministry officials disagreed sharply with his article and insisted that Poland would not accept "political conditions" for the resumption of credits.

In an address to the national assembly yesterday, Foreign Minister Jozef Czyrek also rebutted suggestions that the government would yield to Western pressure. Describing U.S. sanctions as "a violation of international law," Cryzek said U.S. policy was "doing harm to American-Polish cooperation. Such a policy is unacceptable for any sovereign state which respects its dignity."

Western analysts noted that Olechowski's article appeared in a newspaper edited by Deputy Premier Mieczyslaw Rakowski, who is considered a moderate. It is not known whether Rakowski agrees with Olechowski's views. But given the tight press controls in force, it seems likely that publication of the article must have been sanctioned at a high level, if only with the aim of stimulating debate on the subject.

Since December, Polish authorities have pursued a cautious wait-and-see strategy. The military leader, Gen. Wojciech Jaruzelski, appears determined to do nothing that might jeopardize the dominant political position he has won since imposing martial law. He evidently believes that he can afford to wait out Solidarity.

Politically, this may be true. Economically, however, time seems to be running against Jaruzelski. Olechowski's article provides an insight into the economic pressures that have been building and are likely to increase in the months ahead.

Citing a forecast drawn up by his institute, Olechowski predicts that, even making optimistic assumptions, national income will fall between 17 and 22 percent this year. This follows drops of 2 percent in 1979, 4 percent in 1980 and 12 percent last year.

"It is impossible to predict the socio-economic consequences of the income reduction other than to say that they will be dramatic," Olechowski writes.

The main reason for Poland's catastrophic economic decline, the report makes clear, is not industrial disruption caused by Solidarity but the country's inability to finance essential imports. This has been caused by the earmarking of virtually all Poland's export earnings for the payment of interest on the country's $26 billion hard currency debt.

According to government figures, Poland's debt obligations in 1982 alone amount to $10.7 billion. Unable to pay for the imports of vital components and raw materials, Polish factories have steadily cut production. Thus, despite increased coal production since martial law and government claims of improved labor discipline, industrial production has continued to fall sharply this year.

The stock response of most officials when confronted with such gloomy statistics is that Poland can still count on its "real friends" in the Communist world for its rescue.

But it is very doubtful whether Soviet assistance to Poland will be sufficient to reverse the downward trend. Despite the big publicity given by the official news media to promises of Soviet support for Poland's shattered economy, few concrete details have emerged yet.

Olechowski's income projections are based on the assumption that the Soviet Bloc will agree to finance a trade deficit with Poland of between $2.7 and $3.4 billion--25 percent higher than last year. The other assumption is that the West will provide new credits of between $2.2 and $2.6 billion.

Both these assumptions seem overly optimistic. According to Olechowski's data, Western restrictions mean Poland will have access to between only $700 and $800 million worth of credit this year.

Choosing his words carefully, Olechowski writes, "It does not seem probable that the socialist countries--given their present economic and balance of payments situation--could come to our assistance with the amounts necessary to support the level of production and the population's living standards."

He calculates that the extra assistance, above and beyond the projected trade deficit, would have to total between $3.2 and $4.4 billion and would have to be supplied partly in hard currency and partly in products that already are in very short supply in the Soviet Bloc.