Guerrilla leader Robert Mugabe narrowly escaped injury today when 80 pounds of remote-controlled explosives were detonated under a convoy of cars taking him to the Fort Victoria Airport in southern Rhodesia.

It was the second apparent assassination attempt on the black leader who made a triumphal return home two weeks ago after almost five years in exile. Last Wednesday, a grenade was thrown at Mugabe's Salisbury home.

Meanwhile, the British Governor, Lord Soames, today took his first punitive action against one of Mugabe's parliamentary candidates under measures the British executive announced last week to combat voter intimidation.

This action is likely to exacerbate further the already bitter relations between Mugabe and the British colonial adminstration that have kept the transition period to independence here tense.

More than anything else, today's attempt against Mugabe's life illustrates the volatile and hostile warbred atmosphere in which the Rhodesian election campaign is taking place. It also brings into relief the delicacy of the cease-fire agreement reached under British auspices.

Mugabe's death would almost surely sound the death knell for that truce. It would trigger a mass exodus of his 17,000 guerillas from the assembly points where they have gathered and a resumption of the seven-year-old bush war.

Mugabe was on his way back to Salisbury from a campaign rally in Fort Victoria. As his convoy drive down the airport access road, the explosives, set in a large drainage pipe under the paved road, were detonated by a remote control switch about 90 feet away, the police said.

Five members of the Zimbabwe African National Union party were taken to the hospital for treatment of minor injuries and shock, the police said. One vehicle had minor damage, witnesses said.

"It's a miracle anyone is alive," said a witness who estimated that the hole in the road left by the blast was 10 feet deep and 30 feet wide.

A police helicopter was in the air over scene within minutes, but no arrests have been made. Mugabe had canceled a planned rally and press conference at the tourist site of the Zimbabwe ruins because of the security situation, he had told reporters before the explosion.

Through a spokesman, Soames said he was "shocked and horrified at the attempt on Mugabe's life," and he had urged police to "pursue the investigation with all speed and vigor."

But Soames' proscription on campaigning by Enos Nkala, one of Mugabe's candidates, is likely to add insult to the unnerving near-injury of Mugabe today.

Nakala, who once compared Soames to Hitler, has been prohibited from attending any public campaign functions and from canvassing for votes in any way because of his public statements that the war would resume if Mugabe's party did not win the election, a spokesman for the governor said.Nkala remains a candidate for his parlimentary seat.

The action against Nkala was taken under the measures that Soames announced last week to halt widespread voter intimidation. But there are fears in Mugabe's party that they will be used selectively to hurt their polling chances and, as Mugabe put it today at a press conference, to "tip the scales in favor of my opponents."

At a campaign rally earlier in the day, Mugabe's Zimbabwe African National Union and its guerrilla army, the Zimbabwe African National Liberation army. He warned the British governor that if he used "those powers to ban ZANU from participating in the election, then ZANU would hold itself absolved completely from its committment to the Lancaster House agreement," which was signed in London in December.

"He cannot have it both ways; ban us and expect us to be committed to a cease-fire. I am saying Lord Soames must choose -- it it war or peace?" Mugabe told his supporters.

Mugabe later hinted to reporters that if his party was banned from the election in any one particular district, he would order his guerrillas to go back to the bush and fight. He did not say what his party would do in reaction to a ban on campaigning against a candidate.