Pope John Paul's expressed wish that Slavs throughout the world should be able to hear his message from Poland is being fulfilled despite obstacles placed by Eastern European authorities.

A virtual news blackout on the visit has been imposed by the Communist authorities, but the Polish-born pontiff's words have been trickling through to the estimated 40 million Roman Catholics in the region by way of foreign broadcasts, religious newspapers and church pulpits.

The major reporting back to Eastern Europe of the papal pilgrimage has been done by Western radio stations such as the British Broadcasting Corp. (BBC), Voice of America (VOA) and the U.S.-financed Radio Free Europe (RFE).

For example, when the pope urged Poland's bishops in a toughly worded address yesterday to press for further religious freedoms, his words were considered too sensitive politically to be reported by the official media anywhere in Eastern Europe. But they were promptly broadcast back to the region by the BBC and RFE in half a dozen Slavic languages.

The BBC and VOA are not jammed but Radio Free Europe is jammed in Bulgaria, Czechoslovakia, and to a lesser degree Poland and in Polishspeaking parts of the Soviet Union.

But while annoying to the listener, the interference is rarely total - and one frequency is always left free so that it can be monitored by Communist officials.

The pope drew attention Sunday to barriers to the free exchange of information when he declared in Gniezno: "It would be sad to believe that each Pole and Slav in any part of the world is unable to hear the words of the pope, this Slav."

In Poland, the official press and television stations have devoted considerable attention to the visit. But there have been few crowd shots and coverage has concentrated mainly on his references to patriotism, national unity, and the struggle for peace - all themes cherished by the Communist authorities. The pope's repeated calls for greater religious freedoms have largely been ignored.

By and large, the rest of Eastern Europe has taken its cue from the Soviet Union, which reported the pope's arrival in Poland as priefly as possible and showed a short television news clip of his meeting with Polish leaders. The Soviet Union has continued its customary jamming of U.S.-financed Radio Liberty.

The main exceptions to the pattern are Yugoslavia, the only East Uropean country to have full diplomatic relations with the Vatican, and East Germany, where the papal visit has been downplayed by the Communist Party press but given enthusiastic attention in the Christian newspaper, Neue Zeit.

The Yugoslav press is the only one in Eastern Europe to mention the political implications of the pope's pilgrimage, pointing out that his talks with Polish leaders would touch on the sensitive area of church-state relations.

Ironically, the gaps in official coverage have provided the Western radio stations with an opportunity to increase their listeners. It will take up to six months before audiences can be properly gauged, but a spokeman for RFE in Munich said they expected an increase in the station's regular daily listenership in Eastern Europe. The regular audience is estimated at 25 million.

Today RFE's Polish service devoted some 13 out of 19 hours airtime to papal coverage, including a live broadcast of his mass for the Catholics of Upper Silesia and a report on growing complaints over the way the visit has been handled by Poland's official television stations, RFE's five other East European language services also continued to report the visit extensively.

The Voice of America has also stepped up its coverage of the papal visit, beaming several specials and indepth reports to Eastern Europe, as well as full accounts of many of the religious services.

VOA has a reporter and a technician with the pope but RFE has no one in Poland for the visit.

During his tour, Pope John Paul has gone out of his way to stress that he is not just a Pole, but a Slav. It has been left ot the foreign radio stations, however, to pick up his specific references to individual Soviet Bloc countries such as Hungary and Czechoslovakia.

Here is a survey of how individual East European countries have treated the visit.

East Germany (more than a million Catholics): Coverage in the official press is devoted mainly to the Pope's talks with Polish leaders. East German television showed a four-minute film of the pope in Warsaw. A special correspondent reporting from Poland for Neue Zeit called the visit "an event of great religious and national significance."

Largely because of its active Lutheran church, its dominant religious sect, East Germany has gone further than most other Soviet bloc countries in allowing believers access to the news media.

Czechoslovakia (estimated 8 million Catholics): Coverage has been confined to a brief news agency report published in Prague's five daily newspapers on the pope's arrival in Poland TV news carried a 30-second film.

Hungary (estimated 6 million Catholics): Coverage has been limited to agency reports of the pope's arrival without further comment.

Ironically, Hungary gave reasonably full coverage to Pope John Paul's election last year. It has also made rapid strides in improving relations with the Vatican, by pursuing a relatively liberal policy toward religious education and allowing all Hungarian bishoprics to be filled.

Yugoslavia (estimated 7 million Catholics): Several Yugoslav newspapers sent special reporters to cover the visit and television news bulletins carried shots of the pope's tumultuous welcome in Warsaw. Coverage since then has been virtually nonexistent and no mention was made of the pope's call for freedom of information.

Bulgaria and Romania (both predominantly Orthodox countries): Coverage very scant. CAPTION: Picture, Pope John Paul says mass in Czestochowa in front of the famed Black Madonna at Jasna Gora monastery. UPI