Reacting cautiously and with few official statements, the NATO allies consulted closely today with each other and the United States about the imposition of martial law in Poland.

These consultations will continue Monday at a special meeting in Brussels of the NATO ambassadors of the 15 alliance countries and at a previously scheduled two-day meeting of the foreign ministers of the 10 European Community countries in London, according to European diplomats. All of the Common Market nations except Ireland belong to NATO.

Diplomats said they did not expect the allies' immediate response to the martial law in Poland to go much beyond reiteration of recent statements like that in the communique of the semiannual meeting of NATO foreign ministers in Brussels last week. Referring to the 1975 Helsinki accords on human rights, it said, "The Polish people must be free to solve their problems without outside interference or pressure of any kind."

Poland was otherwise ignored in most public discussion at last week's meeting. Informed sources said the NATO foreign ministers decided in restricted session to try to avoid tough alliance statements that could be used by the Soviet Union as a pretext for military intervention.

European analysts noted today that the move by the Polish government this weekend, which had not been entirely unexpected except for its timing, did not appear to have been accompanied by troop movements in either the Soviet Union or other Warsaw Pact countries.

The key question, a number of analysts agreed here today, was whether there would be widespread public defiance of martial law in Poland, particularly violent clashes between Solidarity backers and security forces, that might eventually force a reluctant Soviet intervention.

NATO foreign ministers warned the Soviets a year ago about the consequences of invading Poland. They drew up a secret list of nonmilitary alliance countermeasures, believed to include breaking off East-West nuclear arms-reduction talks, other negotiations and food aid. They also agreed to meet to consider taking these steps if there was outside military intervention in Poland.

NATO diplomats have since acknowledged privately that they were less certain about how to react in the event of an internal military crackdown, like the one apparently under way. They have noted, however, that Poland is heavily dependent on Western trade, aid and bank credits, which now total more than $24 billion. Poland also is seeking emergency food and medical aid from the West for the winter.

But questions remain about how any of this leverage could be used, if it all, according to diplomats and politicians.

"It would be wrong to cut food supplies from the West, on humanitarian grounds," said British member of Parliament Eldon Griffiths.

"The Poles would go hungry and starve," he said. "More hunger could create more riots and thus increase the danger of Soviet intervention."

Food aid is likely to be high on the agenda for the foreign ministers of the Community, through which much Western food aid has been channeled. The NATO meeting is likely to focus on the need for any further statement on the crisis.

U.S. Secretary of State Alexander M. Haig Jr., still in Brussels following last week's NATO meeting there, sent secret personal messages on the crisis to all his NATO counterparts. West German Foreign Minister Hans-Dietrich Genscher said he spoke by telephone with Haig, French Foreign Minister Claude Cheysson and the British foreign secretary, Lord Carrington.

After the NATO foreign ministers reportedly concluded last week that the Soviet Union had decided it could not bear the diplomatic or economic cost of military intervention in Poland, Cheysson told French reporters that Moscow and the Polish authorities had been discussing the crisis more in political terms.