The once-promising talks between North and South Korea bogged down today in angry exchanges, with each side accusing the other of trying to scuttle negotiations over the issue of alleged military provocations aimed at the South.

The South's delegates at a meeting in Panmunjom objected strongly to three incidents in which they said armed Northern infiltrators were stopped from entering the South last week.

They said it would be difficult to continue the talks if more incidents occur, but stopped short of threatening to break off the meetings and agreed to meet again on April 18.

The North's delegation was reported to have charged the South with fabricating the incidents as an excuse to scuttle the dialogue, which began in February with the mission of arranging a meeting of the two countries' prime ministers.

No progress was made in the talks. The charges and countercharges produced an impasse and revived many of the old suspicions and hostilities that have kept the countries apart since the Korean war ended in 1953.

Neither side wants to bear the onus of breaking off the preliminary discussions, which until today had been conducted in a friendly atmosphere, with both delegations making minor procedural concessions to keep things going.

But both are now seeking positions from which each can blame the other if the talks are broken off. And each explains the other's deceit as reflecting internal division.

The South has accused the North of trying to infiltrate in two incidents along the Demilitarized Zone and in a "spy boat" sunk off the southeastern coast after a shooting exchange on March 25. The South's explanation is that its communist enemy is trying to cause "social unrest" to add to the strife that followed last year's assassination of president Park Chung Hee.

If the South's versions are accurate, the incidents are baffling and indicate the North has had new thoughts about continuing the dialogue. For a time after the talks started there were no reports of incidents although they have been common in previous years. The talks came about at the North's initiative and were kept alive largely by its concessions, leaving the impression that Pyongyang wanted a period of harmony in which to pursue talks leading to unification.

Outsiders know little about the politics of Pyongyang and there is no way of telling whether the government of Kim II Sung has suddenly had a change of heart. One South Korean authority hinted today of an internal struggle under way in the North with the Communist Party and the military at odds over how far to go in an rapprochement with the South.

Similarly, the North's representatives claim the South is fabricating the incidents because of its own internal troubles. In Tokoyo, sources who usually reflect the North's viewpoint insisted today the South "invented" the incidents in part as a device to cover up continuing military division and to achieve unity by reviving the old "bogey man" of a communist invasion.

These sources claim to have evidence that skirmished among the South's military factions have continued ever since the Dec. 12 incident in which a group of younger generals ousted the older leadership.

They claim a fire fight between the factions occurred near the demilitarized Zone on March 27, a few hours before the incident in which the South claims northern infiltrators fired on the South's soldiers. The sources asserted that skirmish was witnessed by North Korean border guards.

The North Korean sources also contend the "spy boat" incident was a fabrication because the South has produced neither the boat's wreckage nor any bodies of drowned seamen.

After the "frogmen" incident, in which infiltrators were allegedly stopped after they swam the Han River, the South produced evidence in the form of a wireless radio, a Czechoslovak rifle, and other items. The North has branded this "faked" evidence.

The alleged incidents have become entangled in a surprising way in South Korean politics. Dissident leaders, including opposition party leader Kim Young Sam and former president Yun Po Sun, suggested over the weekend that the talks at Panmunjom be broken off because of the military provocations. While deploring the attempted infiltrations, the South's government has not called for a cessation of talks.

As reported by one of the Southern delegation representatives, Lee Dong Bok, an incident today at Panmunjom shows how close the two sides have come to ending the talks.

Lee told reporters that after the South had protested the infiltrations, one of the North's delegates produced one of several position papers and began reading from it. The text blamed the South for initiating a break-off of the talks and had clearly been prepared on the assumption the South would walk away from the table.

When the South insisted it was not breaking them off, Lee told reporters, the North's delegate promptly pulled out a different position paper and began reading from it.