The grocery market of the Guyana Stores complex, the stout downtown landmark of this small South American capital, offers concise evidence of what has been happening here in recent times.

Its dominant feature is empty shelves.

Bags of frozen fish and a few two-pound chickens are stacked at the far corners of a long, mostly vacant row of refrigerated bins. There are many shelves of bananas, sacks of rice, and loose cellophane packages of curry powder.

There is no bread, no wheat flour, no margarine, cooking oil, cheese, eggs or milk. Cabbages, tomatoes and coffee sell for luxury prices. A sign reads, "Sorry, no beef available." The shortages are no temporary phenomenon. Once the most prosperous, best educated and most attractive of the former British West Indian colonies, Guyana has become a desperate place where economic disaster is the norm and food supplies the biggest political issue.

Each day, thousands of families in this nation of about 700,000 people struggle to piece together a basic diet from supplies of food that human rights groups charge are grossly inadequate.

All the while, the authoritarian government of President Forbes Burnham haplessly meanders between western capitalism and an exotic "cooperative socialism" in an increasingly frantic effort to reverse the decline.

"Every year, people here say that the situation here can't get any worse," said one diplomat. "But every year, it does. There may be no bottom."

The roots of this trouble blend the classic ills of developing post-colonial societies with international interventions and bitter racial divisions. A country the size of Idaho, whose largely unoccupied interior provided the site of the 1978 "Jonestown massacre" by the People's Temple cult, Guyana borders Venezuela and Brazil but behaves like the Caribbean islands to which it is linked by English language, history and British colonialism.

Burnham, a London-educated lawyer who drew on a black political base to found the People's National Congress, took power two years before Guyana's 1966 independence with the help of U.S. and British administrations determined to block the leadership of the majority East Indian-supported People's Progressive Party of Cheddi Jagan, a pro-Moscow Marxist.

Since then, Burnham has maintained himself in power with elections marked by charges of fraud, proclaimed himself a socialist, sought prestige abroad among nonaligned countries and presided over one of the hemisphere's most precipitous modern economic declines.

The figures alone are astounding. Production of Guyana's three major products, bauxite, sugar and rice, has declined between 30 and 50 percent since the mid-1970s, in large part because of government mismanagement, although depressed bauxite and sugar markets have not helped. Per capita income, which fell at an annual rate of nearly 5 percent between 1975 and 1980, has dropped by at least 25 percent more since then, ranking Guyana with Haiti and Bolivia as the poorest countries in the Americas.

After borrowing heavily from banks, western governments and multilateral agencies in the 1970s, the government is now bankrupt and hundreds of millions of dollars in arrears in interest and principal it cannot pay. The United States has suspended all new assistance to the country because of $10 million in overdue debts, and other donors have frozen their aid levels.

The financial crisis has provoked a characteristically hybrid government response. On the one hand, Burnham has made a show of refusing to accept a stabilization program with the International Monetary Fund and of seeking closer ties with communist countries such as Cuba, North Korea, China and Bulgaria.

"We are developing relations with socialist countries who don't regard IMF agreements as a precondition for relations," said Foreign Minister Rashleigh Jackson. "At the moment, we don't see an IMF accord as acceptable."

At the same time, however, the government has been gradually implementing some of the economic measures required by the IMF, such as devaluation, and is seeking to salvage some of is major industries with the distinctly unsocialist tactic of hiring foreign companies to manage them.

"The differences we had with the IMF were not so much the kind of changes but the magnitude," said Finance Minister Carl Greenidge, who confirmed that the government is considering awarding a management contract for its crucial bauxite industry to Reynolds Aluminum or some other foreign firm. "Insofar as the fund and we are able to conclude an internally consistent package, we will do so."

The mixture of rhetoric and pragmatism and of socialist and capitalist policies has produced curious sights around this town of white wooden clapboard architecture and Dutch-built dams and canals. North Korean calendars, posters and books prominently adorn government offices, and a team of North Korean technicians has moved into a rice research center built and still maintained by the United States.

At the same time, a highly touted "cooperation project" between Guyana and Libya to farm rice is quietly being managed by Crown Agents, the British colonial company. Much of the news in the sole, government-controlled daily newspaper comes from Tass, the Soviet agency.

For average citizens, the confusion of the government's politics is of far less concern than the rapid deterioration of once comfortable standards of living. "Everything is falling apart," said Gordon Todd, a labor leader and government opponent. "Education, health, transit, electricity, sewer service -- you just name it, and it's not what it used to be."

Increasingly, government critics say, the principal concern of Guyanese has been food. In part because of a lack of foreign exchange and in part for political reasons, the government has prohibited imports of wheat and other staples since 1982 and has increasingly restricted supplies of milk.

The result is that many common food items are now only available on Guyana's booming black market at exorbitant prices. Meat sells for around $3 a pound, cheese for up to $1 an ounce, margarine for more than $6 a pound and bread $1.25 for a small loaf. Salt, cooking oil, eggs, tea, soap and, frequently, milk are similarly unavailable or out of reach for the average worker, who makes less than $3 a day.

Political opponents hope that the food issue will bring down Burnham, who has managed deftly to suppress all serious opposition to his rule until now. But even the most hopeful of government opponents concede that Guyanese politics remains dominated by Burnham and the Jagan and that little change may be possible while the two aging leaders remain active.