More than a week after armed dissidents kidnaped six foreign tourists to enforce a political demand, Zimbabwe stands on the brink of a tribally based conflict that could dim its bright promise of leadership in African economic advancement.

The kidnapers said they were followers of opposition leader Joshua Nkomo, and threatened to kill their hostages--two Americans, two Britons and two Australians--if the government of Prime Minister Robert Mugabe does not release certain political prisoners.

If the hostages are killed, Mugabe will take firm action against Nkomo's party, "taking in both the guilty and the innocent," said a long-time participant in Zimbabwe's struggle for black majority rule.

The six men, ending a trip through Africa, were abducted on the road from Victoria Falls to the provincial capital of Bulawayo in southwestern Zimbabwe July 23.

Mugabe has blamed Nkomo's Zimbabwe African People's Union (ZAPU) for the kidnaping and said "the swords are drawn" between the government and the party. Yesterday he said Nkomo would be strongly dealt with, an indication that the leader of the minority Ndebele tribe and one of the founders of the Zimbabwe liberation movement might soon be arrested.

Imprisonment of Nkomo, regarded as virtually a king in Matebeleland in southwestern Zimbabwe, could throw the country into a cauldron of violence since there are believed to be more than 2,000 well-armed dissidents, many deserters from the Army, who support him even though he has disavowed their violent acts.

Hostility between the majority Shona tribe, led by Mugabe, and Nkomo's Ndebele dates back a century, but until the achievement of black majority rule two years ago it usually was subordinated to the effort to end white rule.

There is little question that the government has the power to crush ZAPU, but the cost of a new guerrilla war to this fledgling nation could be staggering.

Since independence in April 1980, Zimbabwe has been regarded as a potential model of black-white cooperation in a socialist-oriented economy welcoming Western investment and tourism.

That dream would undoubtedly dissipate, at least for the time being, in the event of a major armed conflict.

A former Nkomo supporter, now out of politics, said he is not optimistic that a clash can be avoided. The government has rebuffed Nkomo's calls for joint action to end the violence and seems fixed on a confrontation course, he said.

Eliminating ZAPU by force would take a long time and result in a permanently disaffected minority, he said.

Just how hard it is for the government forces to completely control Matabeleland was illustrated again this weekend when dissidents robbed a mine 10 miles north of Bulawayo, killing two men, despite the presence of a 4,000-man military task force in the restive province and regular military sweeps through Bulawayo's black townships.

At a party in one of the townships last night an Ndebele school teacher, who declined to be identified, complained that the government is trying to crush ZAPU rather than work for the good of the country.

"They don't know our people," he said. "We will be silent for a while but if they push us too far we will fight."

In many cases, loyalty to tribe overrides allegiance to government. A policewoman, who was a guest at the party, told her friends not to let her hear their criticisms of the regime, because she was supposed to report any such statements.

Even if the hostages are released unharmed, Mugabe may well have gone too far down the road of confrontation to turn back.

The government appears to be losing local support because of harsh tactics used by troops as they search for the dissidents.

As the kidnapers have forced their hostages to walk dozens of miles through the dense, hot bushland to avoid the military, the local people helped them.

Using methods they learned during the long guerrilla struggle, they obliterated the tracks of the hunted men by driving their cattle over them. Apparently they have also provided food, clothing and shelter.

The irony in the use of guerrilla tactics against the government of Mugabe, the ex-guerrilla turned prime minister, has not been lost on analysts. Several note that Mugabe more and more is using the methods that Ian Smith, prime minister in the white government, employed to crush his opponents.

They are careful to point out a major difference, however: Mugabe is the head of a legally elected government battling against the survivors of a guerrilla war that left arms in the hands of thousands of ex-combatants. Smith headed an illegal white oligarchic government, unrecognized internationally, which fought to prevent majority rule.

Smith abandoned democratic principles in the name of security, detaining indefinitely without trial about 2,000 blacks at the peak of the war. Black townships were surrounded by the military and searched regularly, just as Bulawayo townships are being searched now.

Just as in the past, the rule of law seems to be at stake.

Mugabe threatened "extralegal" measures against ZAPU last week and told Parliament, "The government cannot allow the technicalities of the law to fetter its hands."

Last month the government promulgated a law, using emergency regulations to bypass Parliament, that grants legal immunity to officials and the security forces for any action taken "for the purposes of preservation of the security of Zimbabwe." It was such a law passed by the white government and repealed by Mugabe that allowed the acquittal of former Manpower Minister Edgar Tekere in the murder of a white farmer two years ago.