Twiddle the knob of a short-wave radio set here and you soon come across an electronic screeching that grates on your teeth like sharp nails scraping a blackboard. Occasionally the noise dies away, and you hear the voice of broadcasters speaking in Polish from Munich, Washington, London or Paris.

Here lies the front line of one of the most important battlegrounds in Europe today: a struggle for the ears and minds of 36 million Poles. But each side sees the battle in very different terms.

Polish government spokesmen insist that Western radio stations broadcasting to Poland are engaging in blatant psychological warfare. The goal, they say, is to undermine the communist system at its weakest point as a preliminary step to the attempted dismantling of the entire Soviet Bloc.

The broadcasters, by contrast, maintain that their primary purpose is to fill the information gap in Poland caused by strict censorship and the imposition of martial law last December.

Over the past few weeks, following a renewed outbreak of strikes and street demonstrations in Poland, controversy once again has surrounded the role of Western radio stations like Voice of America (VOA) and Radio Free Europe (RFE). Both stations are U.S.-financed and both broadcast in Polish to Poles.

Poland's military government puts much of the blame for the rising tensions on the radio stations directly. In a recent speech, the Polish interior minister, Gen. Czeslaw Kiszczak, said that Radio Free Europe was "instructing and inspiring" an antigovernment conspiracy by giving publicity to pamphlets and statements issued by the suspended Solidarity trade union.

In an interview here, a Polish Foreign Ministry expert on "Western propaganda" accused the radio station of announcing in advance times and places of illegal demonstrations or strikes against martial law. The official, who asked not to be named, said this amounted to disguised "incitement" of Poles to disobey the communist authorities.

The charge was dismissed as absurd by the head of Radio Free Europe's Polish section, Zdzislaw Najder, in a telephone interview from Munich with Washington Post Bonn correspondent Bradley Graham.

"It is our duty to tell the Poles what they say themselves. We never issue appeals of our own. We sometimes even try to tone down some of the Solidarity bulletins, never changing the substance but perhaps trying to sound a little less emotional," he said.

At the nub of the controversy is the fact that Western radio stations are very widely listened to in Poland. Despite heavy jamming from Polish and Soviet transmitters, both RFE and VOA are clearly audible in Warsaw and other Polish cities at certain hours.

According to a survey conducted on RFE's behalf before martial law among Polish visitors to the West, an estimated 17 million Poles (63.5 percent of the adult population) tuned into the Munich-based radio station at least once a week. VOA had an estimated 9 million listeners a week, the British Broadcasting Corp. 6.7 million, and the Voice of Germany 3.5 million.

No audience surveys have been carried out since the military takeover, but RFE officials believe that the total audience may even have increased.

Regular campaigns are conducted in Poland for schools, factories, and the mass media to discourage people from listening to "subversive" radio stations. But it doesn't seem to make much difference.

The Polish Foreign Ministry expert conceded that there is "a lot of interest" in stations like RFE and VOA -- which he attributed to "mistakes" made by Polish propaganda under the now-discredited regime of Edward Gierek. At that time, the official mass media never mentioned the word "strike" and portrayed Poland as an almost idyllic country moving from one economic success to another.

"We are trying to develop a new propaganda formula based on speed and correct information -- but it takes some time before you can get people to believe you," the Foreign Ministry expert said.

The Foreign Ministry official said he himself listened to Western radio stations regularly as part of his duty. His secretary, however, said she tuned in "to hear what they have to say," adding hastily "even though I don't agree with it."

Polish officials distinguish between RFE and VOA. Their special venom is reserved for RFE, which they describe as a rabidly anti-communist organization closely linked to the Central Intelligence Agency. Among the more lurid allegations printed in Polish newspapers over the past few months is that RFE keeps a "black list" of thousands of Poles earmarked for imprisonment or "liquidation" in the event of a successful uprising against the government.

Apart from the official Polish news media, the main source of information for VOA and RFE are the reports of 30-odd Western correspondents based in Warsaw. Sometimes entire dispatches are broadcast. This has complicated the position of American journalists here who see their job as reporting Poland to America, not to itself.

In some cases, the correspondent's material and VOA's own commentary seem to become one in the minds of people here. Authorities have been angered by what might seem a trivial matter in the West. One example has been the use in some broadcasts of the phrase "military junta," which Poles consider highly derogatory, in place of the more neutral "military authorities" used by correspondents aware of its import here.

Several journalists, including this correspondent, have been summoned to the Foreign Ministry and warned about the impact of their reports within Poland.

The Foreign Ministry expert commented: "We say to Western correspondents that they should inform their public about developments here but bear in mind that their information may also reach the Polish public -- and will shape their actions in a specific direction."

The official gave as an example Solidarity leaflets calling for a demonstration in Warsaw on May 3.

"Let's assume that 5,000 to 10,000 such leaflets were distributed here and they reached 100,000 people. After being broadcast on foreign radio stations, that leaflet might have reached half a million people, telling them where to assemble and at what time. This then becomes instigation of unrest, not simply information," he said.

Underground Solidarity activists do not conceal the fact that one of main purposes in distributing their bulletins to Western correspondents here is the hope that this information will be broadcast back, thus reaching a much wider audience.

The Foreign Ministry expert conceded that there would still be tensions in Poland "in the absence of Western propaganda." He said, however, that "the strength and persistence of such tensions are undoubtedly the result of the propaganda."

Najder insisted that, during the Polish crisis, RFE had been "extremely cautious" in its reports.

"We have almost a complex, a hang-up, not to advise, not to encourage, and not to instruct our listeners in Poland," he said, adding that the Polish public, in any case, was more interested in analysis than advice.