The World Bank announced yesterday that because of constraints on its resources, it had decided to apply a tougher policy in "graduating" borrowing-country clients off its rolls.

Senior Vice President Ernest Stern denied that American pressure for a more restrictive policy was "very much of a consideration" in shaping a new policy statement by the executive directors at a meeting Jan. 26. The trigger that starts the graduation process is being kept at $2,650 per capita income (1980 prices), Stern said, although the United States had recommended dropping the benchmark to $2,200.

But he conceded that because demands on the bank's resources are growing, the trigger, which in the past had been applied "quite flexibly," will instead "be applied more firmly and rigorously." The more restrictive policy, Stern said, "will make a very substantial difference over the next five or 10 years."

In the past, nearly all of the countries had achieved a per capita income well above the benchmark by the time they had graduated.

The bank published a table of current clients that showed six borrowing countries enjoying a 1980 per capita income over the trigger. That has now started active discussion of "graduation" for: Oman ($4,380); Trinidad and Tobago ($4,370); Cyprus ($3,560); Bahamas ($3,300); Barbados ($3,040); and Uruguay ($2,820). Yugoslavia is on the edge, at $2,620 per capita.

Six other countries--Argentina, Portugal, Romania, Chile, Mexico and Brazil--had per capita incomes over $2,000, a status Stern said means that their loan programs won't expand very much.

The policy statement adopted at the Jan. 26 meeting said that "graduation should be a flexible and fair process," taking into account special circumstances as they arise. The normal time for moving a country entirely off the bank's rolls is five years after it reaches the benchmark.

The original benchmark of $1,000 in 1970 prices was established in 1973. The $2,650 is based on the bank's calculations of inflation and exchange rate impact. Stern said there had been considerable discussion and some disagreement at the meeting on whether to lower the figure in accord with U.S. wishes.