The U.S. foreign debt soared to $263.6 billion last year, more than twice the amount at the end of 1985 and greater than the total owed by the next three debtor nations combined, the government reported yesterday.

The new figures showed a greater growth in the U.S. foreign debt than most analysts expected, a jump of 135 percent from the 1985 debt of $111.9 billion.

That year was the first time since 1914 that the United States owed more money to foreigners than foreigners owed to the United States. As recently as 1982, the United States was the world's largest creditor nation, with a surplus of $141.1 billion.

The acceleration of the U.S. debt was seen as eroding the United States' political and economic standing in the world. Some foreign policy analysts said that President Reagan wielded less influence at the Venice economic summit earlier this month because of the United States' position as the leading debtor nation.

In addition, economists warned that foreign investors are now able to exert greater influence on U.S. policy decisions. "The Treasury {Department} has to tailor its bond auctions to what Japanese investors want," said C. Fred Bergsten, director of the Institute for International Economics.

"It's menacing. The wolf is getting near the door," Bergsten continued.

The next three largest debtor nations -- Brazil, with $108.8 billion in debt; Mexico, with a $101.6 billion debt, and Argentina, with a $51 billion debt -- rank far behind the United States, although they are considered major economic problems in the world.

The sharp increase in the U.S. foreign debt, which private economists warned can be reversed only with a decline in this country's standard of living and a possible global recession, is likely to figure in the debate as the Senate takes up trade legislation today.

"The U.S. international trade position gives a stark perspective to what is at stake as the Senate prepares to consider trade legislation," said Finance Committee Chairman Lloyd Bentsen (D-Tex.).

He warned that the large U.S. debt "may well mean a return to the days of the late 19th century when British investors caused recessions in the United States by pulling their funds out of this country.

"We must act, and act quickly, to reduce our trade deficit in order to slow, and hopefully one day reverse, our rapid accumulation of debt," he said.

But economists said it will take more than trade legislation to improve the U.S. debt position. Already this year, economists said, the United States has added at least $70 billion more to its debt.

"Now it's over $300 billion. It's growing by leaps and bounds," Bergsten said. "It is on a path that is really explosive. The debt is going to at least double before it starts to level off."

"It's going to be one of the big problems of the decade," said Allen Sinai, chief economist of Shearson Lehman Bros. Inc., a New York investment firm.

"In the long run, the standard of living and the value of the currency is diminished for a debtor country," he said.

Even using the most favorable scenario, Bergsten said, the debt will climb to $600 billion before leveling off, with more realistic appraisals putting the high point at $800 billion. "There is the possibility of it climbing to $1 trillion by 1990," Bergsten added.

By then, he said, interest on the debt will total at least $35 billion a year, a sharp turnabout from 1982, when foreign nations paid $35 billion in interest on the U.S. surpluses. That swing of $70 billion amounts to about 2 percent of the U.S. gross national product, Bergsten said.

"The only way to finance that interest in through an improvement in merchandise trade," where the United States has run record deficits for the past five years, Bergsten continued.

But he and other economists said this will mean a reduction of the U.S. standard of living as Americans produce goods for foreigners instead of themselves. As the United States reduces its demand for foreign goods it also could contribute to a global recession.

Nonetheless, the size of the U.S. economy makes it unlikely that the heavy foreign debt will drag this country down the way it has other large debtor nations.

"We are not the case of a lesser developed country yet. But we can't keep this up forever because our debts are mounting rapidly," said Roger E. Brinner of Data Resources Inc., a Lexington, Mass., group of economic analysts.

The Commerce Department report showed that foreign ownership of U.S. assets jumped by 26 percent last year, to $1.3 trillion. U.S. assets overseas increased by half that amount, 13 percent, and by the end of 1986 totaled $1.1 trillion.