If the organization of African Unity has done nothing else in its checkered 14 years of existence,it has brought the trappings of prestige to the capitals in whcih it has held its summit conferences. Libreville, the site of this year's do, is no exception.

Of course, it helps to be rich, and Gabon's oil, managanese, tropical wood, uranium and iron ore explain why this little country has gone to the top of the league standings.

With the second highest per capita income in independent Africa (Libya is first). Gabon has spent liberally to change this once-charming. French speaking provincial city, known for the excellence of its restaurants, into a carbon copy of almost every other pondescript Westernized boom town from Alaska to Iran.

The high-roofed colonial buildings have given way in the past year of frenzied construction to new super highways, hotels, skycrapers, ministries and conference halls.

President Bongo - who variously calls himself El Hadj. Omar or Albert Bernard depending on whether he wants to impress his audience with his Moslem. Third World or Western credentials - has treated himself best of all.

A conservative estimate puts the costs of his oceanside palace at $250 million. it was built of Carrara marble from Italy instead of the handsome Gabonese variety. Contractors justified the imports by citing the uncertainty of local deliveries.

Part of the problem is that Gabon. with perhaps 600,000 inhabitants in its 102,000 square miles, is sparsely populated. Much of the work gets done by the estimated 30,000 French workers and 150,000 laborers from Senegal, Togo. Benin and other African countries . The Gabonese themselves are not known for their work ethic.

Symptomatic of the Gabonese mood was the interruption of all hotel laundry service from yesterday through Wednesday, the day after the conference is scheduled to end.

"Holidays to honor the conference" was the straight-faced explanation of the French hotel managerial staff brought here on short-term contracts to deal with the crush.

Also recruited for the cause were four French chefs, who found few utensils and staffs made up of eager but untrained high school students. A Bordeaux catering and hotel school helped by providing 40 trainees.

French technical advisers were helping with security, dealing with X-ray machines to examine travelers' baggage and handling walkie-talkies and other imported Western gadgets.

The crush of arriving delegates still proved too much for Gabonese airport officials, and arguments degenerated into fisticuffs as travelers fought to recover luggage from adamant officials.

What's more, there is a certain Puritan streak to the conference which was said to be attributed to President Bongo. All Gabonese women were ordered off the streets by sundown.

Bongo, meanwhile, accompanied his fellow chiefs of state from the ariport in two pearl Cadillacs outfitted with outsized running boards for security guards. A similarly painted ambulance followed the motorcade.

There were complaints from foreigners who were less impressed by Gabon's 30 per cent jump in gross national product than its 37 per cent inflation rate.

A young Tunisian reporter complained that those with limited budgets found it hard to understand why there was no bus service between the city and the conference site, why beer cost $3 at the press bar and why no Gabonese official ever seemed willing to help.

The OAU secretariat itself was criticized when the organization's official spokesman tried to have Agence France-Presse banned from the conference for reporting ideological differences among member states.

Asked if the reports AFP had published were accurate, he replied. "It doesn't matter." Later, he relented and apologized to the French news agency, but emphasized that journalists were not authorized to talk to delegates.

One reporter was retained by Gabonese security officials who found him talking to delegates.

It was in keeping with the mood here that the government canceled all incoming and outgoing flights for the duration of the conference and the day after. Flights to France were excepted, however. The French keep this country going and they were not to be trifled with when it came to their sacrosanct summer holidays.