Poland formally notified Switzerland yesterday that it intended to request the extradition of four gunmen who occupied the Polish Embassy in Berne, but the Swiss made clear they intended to put the men on trial.

The official Polish news agency PAP said the Foreign Ministry told Swiss Ambassador Roger Campiche that the state prosecutor would press for extradition under a 45-year-old treaty between the two countries. But Swiss Justice Minister Kurt Furgler said there was no such extradition treaty. The federal prosecutor's office in Bern opened proceedings against the four on charges of deprivation of liberty.

The Polish-born gunmen, led by Florian Kruszyk, 41, held the embassy for three days but were captured yesterday by Swiss police.

In Vienna, Interior Ministry officials quoted by United Press International said Kruszyk was convicted in 1968 of spying for Poland. Austria confirmed on Thursday that he had served time in jail for robbery. Yesterday, Austrian officials said Kruszyk admitted to having been a member of the Polish secret service between 1962 and 1965. Security officials said it could not be ruled out that Kruszyk still cooperates with the Polish secret service. Swiss officials did not immediately comment.

Kruszyk was portrayed by official Polish newspapers as a hardened criminal with long-standing contacts with Western police services and who was also connected with Western news media. The allegations were made in accounts of the end of the siege, which Poland's official media portrayed as an action inspired by underground opponents of the Communist government and by Western intelligence services.

The Polish Army daily Zolnierz Wolnosci named a series of Western news media it implied had links with the assault on the embassy, including Reuter, The Associated Press, Radio Free Europe, the British Broadcasting Corp. and Radio France International.

The underground leadership of the suspended labor movement Solidarity, in its first reported statement from Poland on the embassy takeover, said, "This provocation is aimed at discrediting our union in the eyes of world public opinion."