Poland's martial-law authorities have moved swiftly to disrupt the free flow of information that had been a central element in the reforms brought about by the Solidarity trade union movement, and they appeared especially concerned about Western media beaming back into Poland accounts of resistance to the military takeover.

The Polish-language service of Radio Free Europe has been jammed at a much heavier rate than normal since Monday, according to U.S. officials. Also, the information about events in Poland that would have fed those broadcasts has been greatly reduced by the cutting of telephone and telex communications with foreign countries.

"This is as unprecedented a degree of temporary disruption of Poland's communications system as has existed," a U.S. official said, referring to the military's consolidation of broadcast organs and newspapers in the country and its control of other means of gathering information.

The official said that problems in obtaining accurate reports have "obviously hampered" U.S. attempts to set policy in response to events in Poland, but he noted that "within our capabilities we have pretty good reporting from people within our consulates and our embassy."

Poland has terminated regional radio and television broadcasts, operating only from the state broadcasting authority's Warsaw transmitter and apparently suspended operations of Radio Polonia, its overseas service, according to several persons who regularly monitor shortwave broadcasts.

By contrast, days after Soviet tanks rolled into Prague in 1968, clandestine radio and television stations continued to broadcast news and anti-Soviet commentaries to the Czechoslovak people. Hungarians also maintained radio communications during their uprising against the Soviets in 1956. In Poland, after the military put down food riots in 1970, regional radio broadcasts kept Polish citizens and Western journalists informed, and Western radio services relayed the information throughout Poland.

"The ruling power has a stranglehold on the radio broadcasts," said Collum Mackechnie of the British Broadcasting Corp.'s monitoring service, which monitors shortwave broadcasts throughout the world and has been listening closely to reports from Poland. He said there has been no sign of clandestine radio activity in Poland.

Some U.S. observers said the military's move to take control in Poland caught Solidarity off guard, and suggested that the independent labor movement might have been overconfident. One radio journalist familiar with Eastern Europe pointed out that Solidarity had negotiated -- and secured to a limited degree -- access to the state-controlled media, which may help explain why there were no clandestine transmitters in place.

A U.S. official noted that such broadcasts would be easy to track down and that the emergency provisions allow the military to confiscate private transmitting equipment.

Communist authorities are always sensitive to the impact of Western broadcasts, traditionally a source to Soviet Bloc citizens of more objective reporting than local news media provide about their countries. In the current Polish drama, the Voice of America, BBC and other Western radio services, lacking accurate information coming out of Poland, have been unable to send as much news back into the country as they did before martial law was declared.

Bill Buell, Radio Free Europe's vice president for U.S. operations, said the source of the increased jamming appears to be in the Soviet Union. The jamming is of the "sky-wave" type, meaning it comes from transmitters that are based about as far away from the listener as those that transmit the programs being jammed. The other type of jamming, "ground-wave," is local. He cautioned, however, that monitoring jamming is never precise.

Officials at the Voice of America and the BBC said their broadcasts do not appear to be jammed. RFE, a U.S.-funded station that beams programs to Eastern Europe, is frequently jammed since it is viewed in the Soviet Bloc as a propaganda arm of the United States.

The military authorities have used other means to control the flow of information into and out of the country. Letters and telephone conversations can be censored, Warsaw Airport is sealed, sales of gasoline have been banned and the movement of Poles and many foreigners has been restricted. Reports reaching Washington from Poland yesterday said censorship is expected to be applied to Western media when their facilities are restored.

According to a Radio Free Europe research report, the national committee on radio and television suspended the second and local radio and television programs and restricted radio broadcasting to a single, centrally scripted, 24-hour program. Local editorial offices were closed, and news is being handled by a small group of handpicked, orthodox journalists.