The attempt by South Africa-based mercenaries to overturn the Marxist government of the Seychelles emerged today as a swashbuckling mission that began after a legendary 62-year-old military adventurist was lured out of retirement, and ended in failure only after a curious Seychelles custom inspector jerked open the false bottom of a suitcase.

South African police confirmed that Michael (Mad Mike) Hoare, a former British Army tank commander who once helped to install Mobutu Sese Seko as president of Zaire, was one of 44 mercenaries arrested Thursday after the Air India jet they hijacked landed in Durban. The group commandeered the plane to escape from a losing shoot-out at the Seychelles Pointe Larue Airport. The battle was unplanned, it turns out, erupting only after authorities discovered automatic weapons in the luggage of what was supposed to be a vacationing rugby team.

South African officials were reported to be "hopping mad" about the coup attempt on the Indian Ocean islands. They insist they had nothing to do with it. "I can tell you most categorically that the South African government was not involved in the plot," Police Minister Louis Le Grange said late last night.

The arrest of longtime South African resident Hoare, who had announced his retirement as a commando-for-hire three years ago, lent an added aura of intrigue to a story already worthy of a distinctive niche among mercenary exploits -- several of which have featured the bulky Irish-born mercenary.

Hoare established himself as a mercenary's hero in the mid-1960s, when he led a small band through 700 miles of jungle in the then-Belgian Congo to rescue 2,000 Europeans, crush the "Simba" rebellion, and install Mobuto as president of what later became Zaire. Since then, the legends surrounding him have inspired a movie -- "The Wild Geese," starring Richard Burton and Richard Harris -- and include such purported exploits as shaking off, without even a change of expression, a ricocheting Simba bullet that creased his forehead.

The latest of Hoare's adventures began, according to press reports here, in Johannesburg, where a mercenary force for the Seychelles venture was recruited from the ranks of former elite South African and Rhodesian soldiers. The band also included men from Britain and New Zealand, press reports have said. The American Embassy confirmed today that at least one American was involved, identified by American journalists here as Barry Francis Gribbon, 26, of Miami.

The men reportedly traveled 300 miles east to Swaziland on a chartered bus, then took a Royal Swazi Airlines flight 2,500 miles northeast to the main island of the Seychelles, 1,000 miles off the east coast of Africa.

The official Seychelles news agency said the men, dressed as civilians and posing as a rugby team, were trying to infiltrate the island in advance of a coup attempt, and that after arriving at the airport, they calmly boarded a bus, planning to be driven to a local hotel.

After most of the mercenaries had already boarded the bus, however, a customs clerk routinely inspecting luggage found weapons hidden under the false bottom of one of the men's suitcases, the news agency said.

A search of all luggage was ordered. "At that moment," the agency quoted a policewoman as recounting, "a big man jumped out of the bus and called out, 'Get down boys.' " As Seychelles police rushed to call for help, the mercenaries unloaded their weapons from luggage on top of the bus and opened fire.

With the apparent advantage of surprise, the mercenaries quickly took more than 100 hostages and began trying to capture the airport. Then, when the Air India jet landed during the commotion with 79 persons aboard, the mercenaries seized it, and as local troops began closing in on the runway, the commandos loaded a dead comrade aboard the plane and took off, the Seychelles agency said.

The commercial Boeing 707 flew under the mercenaries' orders to Durban, Hoare's home for the last few years, where the passengers and crew were released unharmed.

There were conflicting reports on whether any foreign mercenaries stayed behind in the Seychelles, or whether they had local supporters who covered their departure.

The Seychelles news agency said 10 mercenaries, all South Africans, were captured, and that an investigation was under way to determine if other mercenaries had infiltrated the islands before the main group arrived.

A message of apology to tourists from the Seychelles government appeared in a government-owned newspaper today. "That you are not at present enjoying your stay with us is the fault of ruthless men who are prepared to destroy the hard work of a people for their own greed," the message said. The statement apologized for the inconvenience of a curfew which is in effect on the island.

In Johannesburg, South African Foreign Minister Roelof Botha disclosed that his department had been approached "several times" by dissident groups in the Seychelles asking for assistance in overthrowing President Albert Rene.

"On each and every occasion their representatives were told categorically that it was the policy of the South African government not to concern itself with adventures of this nature," Botha said.

"It is no secret that there are at least two dissident groups from the Seychelles wishing to depose the present government of the island," Botha said.

Prime Minister P.W. Botha told the Afrikaans paper Beeld that South Africa rejects "all forms" of hijacking and the police have been instructed "to conduct an intensive and far-reaching investigation into the events.

"After completion of this, action will be taken against those involved in the normal way according to the law," the prime minister added.