Quietly the Polish government, perhaps aided by Moscow, is moving to repay enough of its massive debt to the West to avoid or at least postpone default. ''Since martial law was imposed,'' said a top US bank official, ''Polish authorities have contacted creditor banks to say they are aware of the (debt deadline) situation.''
He emphasized the word ''aware'' and called this a ''beginning contact'' between Polish officials and committees representing the 460 US, European, and other noncommunist banks to which Poland owes $16 billion.
By year-end Poland must pay $500 million worth of interest to the creditor banks, to win a rescheduling - or stretch-out - of $2.4 billion in principal payments which had been due in 1981.
Already, according to senior American bankers and government officials, $130 million to $150 million of the $500 million has been paid to certain of the 460 banks.
(President Reagan in his press conference yesterday indicated the US could do nothing to help Poland solve its economic problems so long as the Polish people are deprived of their rights.)
''There is evidence,'' said a key Reagan administration official, ''that Poland has gotten hold of the $500 million or a large part of it.'' He finds it ''reasonable'' that the Soviet Union might have supplied the money, though no hard evidence of this has seeped through to the West.
It is, banking sources agree, in Moscow's interests to prevent a formal default by Poland, which would cast a chill - if not a freeze - over East-West trade and the flow of Western capital to Eastern Europe.
''The new Soviet five-year plan,'' said a financial expert who has recently returned from a stay in Moscow, ''is based on the assumption of a continued flow of credits from the West.''
Any drying up of Western capital, the source said, would force Soviet officials to revise their development plans. The same would be true in varying degree of other East European Communist states.
Of the $16 billion owed by Poland to Western banks, about $1.8 billion is owed to 60 American banks, mostly large institutions.
''Some small banks,'' said a State Department official, ''have been paid their interest installments - in some cases as little as $50,000 or $100,000, to prevent them from declaring Poland in default.''
A single bank declaring Poland in default could trigger a rush by creditors to ask courts in their respective countries to attach Polish assets, such as aircraft or ships that might be in harbor.
This would cause a breakdown of the debt repayment system, raising the likelihood that creditors would not get their money and that the situation might spin out of control into the whole area of East-West trade and capital transfer.
Western bankers and government officials deny that default, if it came, would undermine the international financial system.
''Obviously,'' said a top official of a leading US bank, ''default would put a big dent in profits. But it would not be a major financial disaster, nor cause any bank to go under.''
Already the Bundesbank, West Germany's central bank, has contingency plans to bail out German banks in the case of default. German banks are more heavily exposed - that is, hold more Polish debt - than any others in the 460-bank consortium. West Germany's Dresdner Bank is the agent for the entire group.
Poland's total Western debt of $26 billion falls into two categories - $10 billion to Western government agencies and $16 billion to the 460 private banks. The US government holds about $1.8 billion worth of the $10 billion official debt, according to US Treasury officials.
Early in 1981 Western creditor governments agreed to reschedule repayment of Poland's official debts, often in the form of credits for food and other commodities.