The Reagan administration is on the verge of initiating emergency food aid to Poland, and is exploring the question of possible parallel East-West long term support to salvage the shattered Polish economy.

Sources in the administration and in Congress confirmed yesterday that both approaches to the crisis in Poland are under serious consideration. The question of emergency food credits to Poland is awaiting President Regan's decision, and will require some form of congressional action. The broader issue of possible loans or credits for Poland in the multibillion-dollar range, by contrast, is in the most preliminary stages of exploration.

In its unique Communist Party Congress this week, Poland is searching precariously for a degree of democracy that can provide Poles with greater freedom and simultaneously forestall the threat of Soviet intervention to crush Poland's year-long experiment in reaching for new freedom within the Communist bloc.

Informed sources said the long-term problem in Poland may be discussed in a preliminary way at the economic summit conference in Ottawa next week. Even raising the question of possible parallel East-West efforts for long-term aid to a foundering Communist economy is virtually unprecedented since the Soviet Union blocked Czechoslovakia from entertaining the Marshall Plan after the end of World War II.

It is improbable, several administration officials said, that the heads of government meeting in Ottawa can do much more at this stage than underscore high western interest in the fate of Poland. At this stage, no one -- including the Soviet Union -- can forecast with certainty what will emerge from the current Polish Communist Party Congress, one senior official said. "Nobody will make any commitments," he said, "until we know where the Poles are going."

Several members of Congress said yesterday that Secretary of Agriculture John R. Block has now "signed on" to a plan to authorize supplying Poland with 400,000 tons of corn in new credits under the Commodity Credit Corp.'s program. The cost of that grain, intended to provide emergency food to Poland and to prevent the collapse of its American-stimulated chicken breeding industry, was previously said to be $80 million. An administration official said yesterday that a recalculation of the cost now puts it at $60 million.

In Columbus, Ohio, where Block yesterday addressed the annual convention of the National Corn Growers Association, he limited himself at a press conference to stating that the question of emergency corn aid for Poland "is being discussed at the highest levels of government."

House Foreign Affairs Committee Chairman Clement J. Zablocki (C-Wis.) said in mid-afternoon that "is is my understanding that just today the secretary of agriculture has okayed the emergency shipment." However, Zablocki said, "there is a problem that has to be resolved on the floor of Congress, by legislation or by [evidence of] legislative intent" to clear the legal barriers to send the corn to Poland.

A prime mover in the campaign to obtain new food aid for Poland, Rep. Edward J. Derwinski (R-Ill.), said "the whole administration is now on board" for the corn shipment. What is under way, Derwinski said, is "a politically non-controversial approach to the Polish problem." He added that in this process, "I do not see anything that would provoke Soviet reaction," and in addition, providing new food aid for Poland "also conforms with [American] agricultural interests."

"I am very optimistic" that the Reagan administration will carry through the food commitment for Poland, Derwinski said. The intention to do so, he said, will be supportive of Poland's political reformers at a very delicate time for the future of Poland. State Department officials said they fully agree.

Another advocate of emergency aid for Poland, Rep. Paul R. Findley (R-Ill.) who is a member of the Foreign Affairs and the Agriculture committees of the House, said that "if it requires legislation, we will try to get it through as a separate piece of legislation." To wait until the new agriculture bill reaches the floor, as some others suggested, Findley said, means waiting "until September" and then entangling the Polish issue in the "highly complex" and controversial legislation on American agricultural.

Administration officials at all levels generally declined to talk for the record at this time on what they are discussing about possible long-term remedies for Poland's massive economic dilemma. Poland's new economics minister, Zbigniew Madej, said in his first public address earlier this month that Poland faces a grueling struggle for at least five years in order to get back to its 1978 level of national income. "Unless we start on economic reform immediately, from today," he said grimly, "nothing can save us from catastrophe, from a total breakdown of our economy."

Various ideas are being canvassed inside the administration about possible western efforts to help salvage the Polish economy. All of them, as one official said in private, "are based on the assumption -- the expectation -- that the Soviet Union will pay its share and that means at least 50 percent." tPoland's current debt to the West is about $26 billion. According to an official American calculation, the Soviet Union during the past year extended to Poland about $3 billion worth of financial and credit benefits, including debt rescheduling, of which "something under $1 billion" was in "hard currency," and the balance in "soft currency" benefits.

What some analysts within the Reagan administration are speculating about is that in order "to save Poland from bankruptcy," in addition to the support in might get from the Soviet Union and other Eastern European nations, it may need something on the order of $1 billion to $2 billion of western loans and credits for several years, perhaps five or more.

"This is all hypothetical," one authoritative official source emphasized. Nevertheless, in embryonic form, specialists are beginning to "try to think through the problem," as one expressed it, "even though there is no specific plan worked out," and "no hard calculations can even be made" by anyone except the authorities in Poland.

Some specialists think it improbably that the Soviet Union ever would agree to permit an institution such as the International Monetary Fund to operate a stabilization plan for Poland's economy; others argue, "what real alternative does the Kremlin have, except [military] intervention?" And that, they underscore, would "only compound the problem for the Soviet Union -- not solve it."

Poland's current failure to meet its commitments to deliver goods and raw materials to neighboring Communist nations already is seriously disrupting their economic planning. Soviet military intervention in Poland would not produce more goods; it almost surely would produce less -- even at gunpoint -- western specialists are convinced, with rippling consequences throughout the Soviet bloc.