The Yugoslav presidency Saturday postponed for two days, at a request of the republic of Croatia, a looming deadline for the surrender of weapons by illegal paramilitary groups that triggered fear of a crackdown.

The eight-man presidency that runs Yugoslavia announced Saturday night that it had met the Croatian request and had extended the deadline until Monday. It gave no further details about the time change in its order.The Croatian and Slovenian republics have rejected allegations that they have paramilitary groups and have been waiting to see if the communist-led Yugoslav army would use their rejections of the order to justify crackdowns against their regimes.

Earlier Saturday, the Yugoslav Defense Ministry issued a notice clarifying confusion over the timing of the deadline to say it would expire at midnight Saturday.

The ruling nationalist parties of Slovenia and Croatia, which ousted communists from power in free elections last April, maintained their positions that the order did not apply to them.

Slovenian Defense Secretary Janez Jansa, in a television address Friday night to the republic's 2 million people, said the order "does not relate directly to Slovenia because in Slovenia there are no illegally armed groups."

He reiterated apprehensions that the army could stage provocative "small actions," but discounted the possibility of "major incidents."

Predominantly Roman Catholic Croatia and Slovenia want Yugoslavia turned into a confederation of independent states because they fear domination of the federation by communist-ruled Serbia, the largest republic.

While Croatia has been reserved in implementing a vow to secede because of the serious frictions with its Christian Orthodox Serbs, Slovenia is moving rapidly to fulfill a December plebiscite for independence.

The presidency's pro-Serbian majority and the military oppose confederation. The army has warned it would use force to preserve a federation based on socialism.

The disarmament order was issued Jan. 9 by Yugoslavia's communist-dominated eight-man federal presidency, which contended that unnamed political parties had created "illegal paramilitary units" along ethnic lines whose existence threatens to exacerbate already-high tensions and push the six-republic federation into civil war.

The presidency ordered such groups to disband and directed that they and individuals possessing military-type weapons surrender them to the army or face unspecified "legal" measures.