The recent takeover of Mobil Oil Italiani by Kuwait Petroleum Co. is only the latest in a trend that has taken over the Italian oil sector - the exit of the multinationals.

In the last decade, the spate of mergers and acquisitions has so far affected 30 percent of oil producers and distributors here.At least nine companies have either disappeared from the Italian market or have been taken over: Amoco, Gulf, Chevron and Texaco, all of the United States; British Petroleum; Holland's Mach and Royal Dutch/Shell Group; and France's Elf Aquitaine and Compagnie Francaise des Petroles-Total.

As a result, U.S. multinationals decreased their share of the market to 10.5 percent today, down from 27 percent in 1980. The share held by European companies dropped to 5 percent, down from 10 percent during the period.

What has prompted this exodus? Petroleum products in Italy are under price controls and leave little room for adjusting to changing markets.

Persistently high costs have put a dent in Italy's competitiveness in the oil market. And although there has been some talk about making gasoline more competitive by reducing distribution costs, no concrete actions have yet been taken.

Furthermore, taxes for refining are high and, barring tax deferrals, result in a heavy financial burden for oil companies operating in Italy.

Like other companies who left the market in the past, Mobil Italia suffered heavy deficits that reached 66.5 billion lire ($53 million) in 1988.

The Association of Private Oil Distributors in Italy summed up the situation this way: "We are forced to work in rigid conditions that have no counterpart in other countries of the European Economic Community."

Finally, there is a great need for investments in the production of cleaner fuel. At present, only government-owned Agip Petroli has a three-year 2000 billion lire ($1.6 billion) investment toward this end.

For the Organization of Petroleum Exporting Countries, on the other hand, whose interests are largely to find markets for crude oil, the Italian market is a growing one.

Arab oil-producing countries made their first foray into the Italian market in 1983 when Libya's Tamoil acquired Amoco and Texaco divisions here. With Kuwait Petroleum's takeover of Mobil, their share is now 13.5 percent and growing.

Indeed, Kuwait Petroleum becomes the third largest company in Italy after government-owned Agip and Ip which hold 88 percent of the market.

Recently, there has been talk about Libya's Tamoil possibly acquiring Erg, the former Chevron division in Italy, which today bears a 200 billion lire ($160 million) debt.