British troops arrived this evening to reinforce local police efforts to quell a three-day bombing and arson spree that erupted in protest against last week's execution of two black political activists.

Minutes before the armed company of 100 soldiers landed on this popular resort island, opposition government spokesmen, who had condemned the hanging as a violation of human rights and due process, issued statements saying the troops' presence was an "overreaction," and could agitate the uneasy calm that prevailed today.

"This situation could create excitement in the veins of some who are already having trouble dealing with the police," said Lois Browne-Evans, leader of the Progressive Labor Party and lawyer for the two men who were executed Friday. "We are appealing for restraint on all sides."

The Bermuda islands are at the same latitude as Savannah, Ga. and about 640 miles to the east in the Atlantic.

The British troops, apparently a highly specialized commando strike team, landed at a nearby U.S. Naval Station. They are expected to stay there unless called out to quell a disturbance.

They will reinforce the islands' unarmed police force of about 380-member Bermuda regiment, which is stationed at another edn of this main island, at the Southampton Princess Hotel.

IF all goes well tonight, a 5:30 p.m.-to-6 a.m. curfew is expected to be pushed back to 11:00 p.m. Monday.

As news of the disturbances spread abroad, expatriate Bermudans began returning home. Tourism dropped significantly as some flights were cancelled because of the curfew restrictions.

On various street corners of this little island, whose neat and coloful homes are nestled among lush green hillsides, helmeted young blacks idly rest on motor scooters and mopeds, conversing in a manner that makes police uneasy.

Since the hangings of the two convicted murderers, scores of arrests have been made for alleged possession of Molotov cocktails - fire bombs that in some cases are fashioned from gallon mineral oil bottles filled with kerosene and stuffed with rags. Other arrests have been made for violations, whiich can draw a two-year prison term.

More than 25 fires were set, causing an estimated $5 million in damage.

"We hadn't figured on anything like this - we were absolutely caught off guard," said one ranking member of the island's equivalent of a national guard.

"We had pinpointed the core, a usually troublesome group of youths, but when we started making our arrests we were picking up kids, small boys on up. We don't know what to make of it," he said.

Nevertheless, Allan Lister, Bermuda's chief police inspector, said he hoped the British troops "will have to do no more than maybe clean up the beaches swim for a bit, then go back home."

Lister estimated that several thousand of the islands' 55,000 residents were either involved in protests against the executions or the violence that followed. Widespread sympathy was generated for the two men because "both were well known," he said.

"This is a racial issue," Lister said."When you get down to the nitty gritty, everything on this island is racial. It is black and white." About 33,000 blacks live here, and 22,000 whites. The whires generally are more wealthy.

Some island businessmen disagreed with this interpretation, saying the troubles were the result of an abundance of undisciplined youths who have nothing better to do.

Chris Szembeck, cive president of one of this island's luxury hotels said, "It seems that the people who five years ago were 12 and 13 years old and do not realize why these men were executed."

At 11:30 p.m. last Friday, despite a week-long protest, prayer vigils and meetings of the "people's parliament." Erskine Burrows, 33, and Larry Tacklyn, 26, were hanged and buried at Casemates Prison on the outskirts of the island.

Burrows, a former member of a now defunct group called the Black Beret Cadres, had been convicted of the 1973 shooting death of Sir Richard Sharples, the governor of Bermuda, and his aide, Capt. Hugh Sayers, on the grounds of Government House. Burrows was also convicted of killing police Commissioner George Duckett in 1972.

AT the times of his trial, according to authorities, Burrows sought to make the people of Bermuda aware of the "evilness and wickedness" of colonial rule. Bermuda is a self-governing British colony.

Tacklyn was also tried for the killing of Sharples and Sayers but ws acquitted. He and Borrows were convicted, however, of killing tow supermarket owners during an apparent robbery attempt in 1974.

The two were executed after the British government, which has abolished the death penalty at home, denied and appeal for clemency. British Foreign Secretary David Owen had suggested that the executions be called off, however.

"This is the only crime where you have a blackharming a white," said one young man, "and they hang them."