Recent immigrants report that increasing bribery of local officials in China has added to a flood of arrivals from China and Vietnam, threatening to engulf all remaining space in this tiny British territory.

Since Jan. 1, at least 80,000 immigrants and refugees have crossed the border from China and about 37,000 have arrived in boats from Vietnam. Both figures are unprecedented in the last three decades and the number of boat-borne refugees here has swelled to 10 times what it was six months ago.

If the flood of people still crammed in rusty boats in the harbor, many of them children, continues increasing at this rate, it could total as many as 400,000 by year's end - nearly 10 percent of Hong Kong's population.

"Where has all our humanitarianism got us?" asked the Hong Kong South China Morning Post in an editorial. "Into a deeper problem of people than at any time in our history."

Authorities have appealed to dozens of governments for help, but the only substantial outflow so far is to the United States. That rate of about 500 a month had dropped recently because of funding delays.

Hong Kong Governor Sir Murray Maclehose appealed to Chinese authorities during a March Peking visit, but there seems to have been no substantial decline in the 10,000 Chinese residents arriving here each month with legal exit permits.

Immigrants confirm a report by the Chinese-language newspaper Ming Pao of an unexpected increase in bribery under China's new, relaxed local administrative procedures.

"Serious corruption exists in the practice of commune cadres in many places, and once they are bribed they would indiscriminately issue permits," Ming Pao said.

Hong Kong authorities, dependent on good relations with Peking, have continued to accept all emigrants with valid exit permits. Hong Kong police have turned back another 31,000 illegal refugees this year, but at least that many more are estimated to have slipped over the border undetected.

Communist sources here report the Peking government plans to cut down on corruption by requiring that all exit permits be approved in Peking, rather than at the local level. Such an order is expected to create a panic among many people wishing to leave China, and perhaps swell the numbers arriving here illegally.

Britain, which runs this territory, agreed this week to take in 982 people rescued off floundering boats from Vietnam by a British freighter, the Sibonga. The new Conservative government in London has made no promise of acceptance of more boat people on a regular basis.

Almost all the arriving refugees, from both China and Vietnam, are ethnic Chinese. Only 20 percent of the boat people are ethnic Vietnamese. The Vietnamese government has continued to pursue its policy of discrimination against its citizens of Chinese origin, particularly since the brief Chinese armed invasion of the Vietnamese border area.

Chinese residents have been organized to leave in boats by Vietnamese officials who collect fees of $1,000 to $2,000 a person. The boat people say they have been threatened with transfers to concentration camps if they do not leave.

More than 200,000 ethnic Chinese have crossed the birder from Vietnam into China, where many have been crammed into state farms. Some of the border crossers have been detected entering Hong Kong overland, although authorities here say they do not know their numbers. Chinese coastal authorities have helped many boat-borne refugees from Vietnam rest and repair their boats on the condition that they continue on to Hong Kong.

Authorities here, despite initial efforts to stop some large freighters full of refugees outside Hong Kong waters, have been far more receptive to refugees than other possible destinations such as Malaysia, Indonesia or Taiwan.

Space has been found in abandoned barracks and dockyards here and officials are considering making parking garages available. As the numbers increase, however, the conditions worsen. Many refugees have had to remain on their boats for weeks.

At the government dockyard at Yaumati, 3,000 people are crammed into one large warehouse. Children crawl about half-naked in nearly 100 degree heat and 100 percent humidity, under a metal roof.

The Hong Kong government estimates it is spending at an annual rate of about $9 million, or about 10 percent of its social welfare budget, just to feed the boat people. This does not include medical expensives or the salaries of police and civil servants handling the inflow.

The United Nations Office of High Commissioner for Refugees, which also handles a substantial part of the cost of housing and feeding boat people here, estimates it has commitments of about 100,000 settlement places a year. This would appear to include a pledge by the Carter administration to take 7,000 a month, but officials here say only about 500 of those per month would be taken from Hong Kong.

About 115,000 refugees from Vietnam and Cambodia were at Southeast Asian way stations a year ago, waiting placement.There are now about 262,000. Other thousands are thought to have died at sea.

The captain of the Sibonga, the British freighter that recently arrived here, said he made up his mind to pick up nearly 1,000 refugees becalmed without water after he saw a baby, dead of exposure and thirst, tossed into the waves.