PANAMA CITY, Panama (AP) _ About 15 armed plainclothesmen smashed a glass door at a law firm on Friday to arrest opposition newspaper owner-publisher Jaime Padilla Beliz, one of his lawyers said.

Padilla's newspaper, El Siglo, an outspoken critic of Gen. Manuel Antonio Noriega, was closed down in July 1987 by the Noriega-controlled government after being accused of undermining the physical and economic security of the state.

Venus Cardenas, of Padilla y Asociados, said the band of armed men picked Padilla up at that law firm after shattering a glass door to get in. She said they took him away in one of the three cars they used.

Padilla is a senior partner in the firm.

Ms. Cardenas said that when she called the Defense Forces security office, a spokesman told her ''we know nothing'' about it.

Virtually all opposition newspapers have been closed.

Noriega, as commander of the Panamanian Defense Forces, is the most powerful man in Panama.

In February 1988, federal grand juries in Florida indicted him on charges of drug trafficking and money laundering, charges he denies.

Economic sanctions and other pressure by the United States to remove Noriega from power have since failed.

Noriega had the government annul presidential elections May 7, which international observers said were won overwhelmingly by opposition candidate Guillermo Endara.

In a statement Friday, Roman Catholic Church leaders said a provisional government that Noriega recently installed was legally unjustified.

Noriega on Sept. 1 named Francisco Rodriguez, 50, head of a provisional government to hold new elections. Rodriguez said he won't call for new balloting until Washington lifts its sanctions on Panama. And the opposition insists its May 7 election victory be honored.

''Far from being solved, the crisis is getting worse,'' the church episcopate said. ''Contrary to all national and international expectations, we have a de facto government which is outside the constitutional framework.

''The only thing that would justify a government that calls itself provisional would be the immediate and direct search for constitutional order according to popular will.''