Border tension between Chile and Argentina has intensifieed as news dispatches from Buenos Aires reported that Chilean President Augusto Pinochet has appealed to Argentina to reduce its troop mobilization in the disputed area.

Gen. Pinochet's request, made in a letter to Argentine President Jorge Rafael Videla, apparently referred to recent Argentine navy maneuvers in the South Atlantic and combat exercises being conducted by the army in Patagonia near the Chilean border.

An Argentine marine contingent reportedly is stationed at a navy base at Ushuaia, on the northern coast of the Beagle Channel, whose delineation is the basis of the dispute.

While a possible war is the subject of cocktail party chatter in both countries, it seems a remote possibility.

According to an arbitration decision reached last year by an International Court of Justice panel, the Beagle Channel, which passes from the Atlantic to the Pacific, flows to the north of three small disputed islands. Under an 1881 treaty between the two countries, that delineation means the islands belong to Chile.

Last week, following an emergency summit meeting between Gens. Pinochet and Videla, Argentina rejected the court's decision on grounds it was based on an incorrect interpretation of the Argentine case.

Queen Elizabeth of England handed down the decision under the provisions of the treaty. On Monday, the reaffirmed its validity through the British Foreign Office.

The dispute continues in a shaky stalemate, with both Argentina and Chile postponing more openly bellicose stands as Argentina military emissaries arrived yesterday for talks in Santiago.

Although the positions of Pinochet and Videla are backed by public and press support in their countries, their individual performances are under strong internal scrutiny within the military juntas they lead.

Currently threatened by a power play from Argentina's navy commander, Adm. Emilio Massera, who gained domestic publicity last month by belligerently leading the fleet into the Beagle Area, Videla must show he is capable of resolving the conflict with some semblance of benefit for Argentina.

Pinochet is in a similarly tough spot. Although he has the strength of the arbitration agreement on his side, the harshness of his intransigent dictatorship over the past several years has earned him many enemies and international support of Chile's position in the dispute has been conspicuously absent.