Despite two recent unity rallies staged with government approval, prospects of a merger between Prime Minister Robert Mugabe's ruling party and that of opposition leader Joshua Nkomo remain clouded in uncertainty, according to political analysts and western diplomats.

A bitter public statement last weekend by Nkomo at the funeral of a longtime lieutenant who had been detained by the government, and an embarrassing public dispute in Parliament that revealed fissures inside Mugabe's party suggest an agreement between the two parties is still distant.

An unusually candid editorial in Thursday's Harare Herald, which often reflects official thinking, said the two recent events "deal crippling blows to the unity talks."

Mugabe himself, in an address Thursday night marking the sixth anniversary of Zimbabwe's independence, called national unity "a fundamental objective." But Mugabe also indicated that Nkomo and his followers must be prepared to join the ruling party rather than have the two sides form a new party -- an issue that has been a major sticking point in the talks.

Many observers believe some sort of agreement is inevitable between the two men, who fell out in 1982 when Mugabe accused Nkomo of plotting a coup and dismissed him from the Cabinet.

Such a pact would clear the way for Mugabe's goal of creating a one-party state, and would give him enough votes in Parliament to abolish that chamber's 20 whites-only seats. Those seats were set up under the agreement that ended this country's seven-year liberation war. Thursday night Mugabe reiterated his commitment to abolishing them constitutionally next year.

Last month, Nkomo preached reconciliation at a public rally in Bulawayo, capital of Matabeleland, his political stronghold. He later appeared on the same platform with a longtime foe, Police Minister Enos Nkala, at a rally in the village of Kezi, scene of recent violence allegedly caused by armed dissidents.

The two men urged public support for the government's campaign against the insurgents, former members of Zimbabwe's Army who deserted and took to the bush after Nkomo's ouster.

As an apparent payoff for Nkomo's new public support, Mugabe met secretly with his political rival two weeks ago. Sources decribed the session as friendly but inconclusive, saying the two men agreed only that negotiators from their parties should reconvene a joint unity committee that has not met for several months.

But last weekend Nkomo lashed out anew at the government at a funeral for Lookout Masuku, commander of Nkomo's forces during the liberation war and deputy commander of the Zimbabwean Army after independence. He was arrested four years ago on treason charges for allegedly stockpiling arms for an Nkomo coup attempt and, after his acquittal in 1983, redetained without charge along with five others.

At the funeral in Bulawayo, Nkomo accused the government of using the same repressive machinery that former prime minister Ian Smith used against black nationalists during the days of white rule.

Nkomo said Masuku had been unjustly imprisoned and he depicted his former aide as a lion who had triumphantly killed the "buffalo" of white-minority rule only to have "hyenas" -- presumably Mugabe's government -- steal the spoils.

The speech followed by a few days a rare public mudslinging match within Mugabe's ruling Zimbabwe African National Union over the conduct of one of his senior Cabinet ministers and potential successors.

It began when Minister of Transportation Herbert Ushewokunze was accused by a parliamentary watchdog panel of corrupt dealings in administering the country's debt-ridden railway network. Ushewokunze, a senior member of the party's ruling Politburo, responded with a five-hour harangue in Parliament against members of the panel. He also accused opponents of fomenting tribal hatred inside the party and conspiring against him.

His accusations brought to the surface one of the party's most taboo subjects -- the extent to which ethnic rivalries still dominate this purportedly nonracial and nontribal society. It also illustrated the depth of bitter personal animosities inside the party, with several of Ushewokunze's potential rivals for power working behind the scenes to discredit and isolate him.

Mugabe moved quickly to restore order, convening an emergency session of the party's central committee last weekend at which he removed Ushewokunze from the Politburo and ousted the minister's chief accuser, ruling party member Byron Hove, from Parliament.

Nonetheless, the Herald editorial noted, the party "has clearly been shaken by the experience and it will take time before things return to normal. Until then, it is unlikely the party will spare a moment for the unity exercise."

Other analysts noted that a party whose leaders are grappling for power among themselves is in no position to absorb an organization like Nkomo's, which has its own internal quarrels. Many in the ruling party fear the delicate balance of forces as well as their own positions could be jeopardized by a merger and have privately opposed it.