In the check-stinging cold just after sunset one night last week, Stefan Korbonski stood on a street cornor in Mount Pleasant, clutching along red candle and softly singing the Polish national anthem.

Rush-hour traffic whipped by on 16th Street NW as Korbonski huddled with his wife and two other Polish Americans two blocks from the Polish Embassy. Korbonski's wife Sofia, wrapped in a camel's hair coat and mohair cap, held a "Free the Polish Workers" placard. Nearby, friends from the AFL-CIO waved "Free Walesa" signs and neighborhood children, attracted by television klieg lights, chanted "One, two, three -- Solidarity" in between licks on candy canes.

Small demonstrations like these are about all that members of Washington's Polish-American community can do now that martial law has been imposed in their homeland. For several nights last week, they held their candlelight vigil at 16th Street and Columbia Road NW. Some nights only 20 people showed up, but one evening the crowd swelled to 300, and there was a brief clash with police as demonstrators tried to edge closer to the Polish Embassy.

Members of the local Polish-American community -- estimated at about 10,000 people -- have suspended their shipments of food and medicine since transportation to Poland was cut off. Now they wait and pray and demonstrate in an effort to draw public attention to the plight of their Polish brethren.

"Poland was transformed into one gigantic prison with 36 million inmates," Korbonski said of the military crackdown on Solidarity, the country's free trade union movement. His eyes watering from the cold and his voice deep with emotion, Korbonski thought back to 1947, when he was a leader of the Polish Peasant Party's struggle against communist rule.

"History repeats, history repeats," he said.

Sofia Korbonski, a retired broadcaster for the Voice of America, said she has little time for demonstrations because she was called back to VOA to help out during the current crisis.

"We were getting a lot of letters from Poland until now. People are really counting on us," said the rosy-cheeked Washington woman who said she worked as a codebreaker for the Polish underground during World War II, and escaped with her husband to the United States in 1947.

Before martial law was declared Dec. 13, Sofia Korbonski said, "I managed to send a lot of parcels, as well as money, early enough so I even got some confirmation it reached our family and friends." She sent butter, canned meats, sausages, woolens and high boots -- the necessities for a long, cold winter.

Others, though, like Stefan Koper of Arlington, have Christmas packages of coffee and cocoa "sitting in our homes, waiting for the opportune moment" to be mailed.

"We're sitting helplessly on the sidelines," said Koper, president of the Polish Veterans Association. "There is no communication, the post office doesn't work, the telephone doesn't work, traveling is impossible. It's unbelievable that in this time and age, the country can be padlocked completely."

Before the events of the past few weeks, the Polish American Congress, an umbrella organization for Polish groups in this country, was sending butter, cooking oil and powdered milk to be distributed by the Catholic Church in Poland, according to Zdzislaw Dziekonski, Washington representative for the organization. American pharmaceutical companies also were donating penicillin, hypodermic needles, sutures and other medical supplies, he said.

Now relief efforts are at a standstill, he said, because President Reagan's policy on shipping food to Poland still is uncertain.

"We are in a quandary because we don't know if it will pass through or not. It's unclear from the Polish side and the American side. We simply do not know what to do," Dzienkonski said.

For the small knot of Polish Americans gathered at 16th and Columbia last week, there was little to do but wait.

"We don't know what will happen next week, we don't even know what will happen in the next day," worried Jan Miska, president of the Washington division of the Polish American Congress.

As they waited, they talked about their faith that Poland's free trade union will survive.

"I am hopeful that sooner or later they will end the martial law," Korbonski said. "Maybe I'm an incurable optimist, but I still expect some compromise between Solidarity and the Communist Party."

And then, with vigor, he translated the words to the Polish national anthem: "Poland will not perish as long as we live."