Journalists from two of Britain's most renowned newspapers were denied bail last night by an Argentine judge who ruled earlier that they will be put on trial for espionage. They face prison sentences of two to eight years if convicted.

The defendants, who have categorically denied the government's allegations, are Simon Winchester of The Sunday Times and the reporter-photographer team of Ian Mather and Tony Prime of The Observer.

They were arrested more than two weeks ago at the Rio Grande airport, which is both a commercial facility and a military air base on Tierra del Fuego at the southern tip of Argentina. Prime was accused of photographing military aircraft and facilities. Mather and Winchester were accused of gathering military information, including a visual reconnaissance by Winchester, who was using binoculars.

Prime's photographs and the notebooks of Mather and Winchester were seized as evidence by military authorities. The three men were then shipped south to Ushuaia for confinement in the territorial jail.

On April 19, federal Judge Carlos Sagastume began preliminary hearings to determine if sufficient evidence existed to bring the journalists to trial. At the start of the hearings he said he recognized that there is often a "gray area" between "the public's right to know" and the demands of military security.

Over the next three days the judge listened to evidence and arguments presented by military witnesses and prosecutors. The journalists were represented at the proceedings by a Buenos Aires attorney, Guillermo Balaban, but they were not allowed to present a case in their own defense. The judge said the sole purpose of the proceeding was to determine if the evidence against the journalists was strong enough to justify their detention and trial.

Friday night, he ruled against the trio, saying that while he did not believe they were "habitual" or professional spies, he did believe they had been acting more as British patriots than as professional journalists.

The judge is a former naval officer whose son currently is commander of a gunboat in the Navy.

In a brief meeting last week with other reporters, Winchester, Mather and Prime denied the allegations and insisted that they had been acting solely as professional journalists.

Their attorney is now in Ushuaia to determine if an appeal will be filed on the ruling by which bail was denied.

The three men, all in their mid-forties, are being held in a cell nine by nine feet. They said last week they had not been mistreated and were adequately fed. The Ushuaia police chief, Jose Baitroso, said their mental attitude is good and they are allowed to exercise.

There is considerable concern among other journalists, particularly in the British press corps, that any trial conducted now would be prejudiced by attitudes arising out of the conflict between Argentina and Britain over the Falkland Islands.

Winchester and Mather were on the Falklands when they were invaded and occupied on April 2 by Argentine forces. They were evacuated to Montevideo, Uruguay, and had only recently returned to Argentina when they were arrested at Rio Grande.