American paper manufacturers plan to increase sharply their ability to make newsprint during the next three years, according to a survey by the American Paper Institute, the industry trade group.

The United States imports about 65 percent of the newsprint it uses each year, and foreign strikes have made newsprint supplies tight and expensives this year.

The strikes came in a year when newspaper advertising showed strong gains -- about 14 percent -- and advertising inserts were being used extensively by merchants. The full impact of the strikes came during the fall-winter period, traditionally the time of heaviest advertising in newspapers.

According to the paper institute study, manufacturers will increase their ability to turn out newsprint by 32 percent during the next three years, from about 4.1 million tons to 5.4 million tons a year. That 1.3 1.3-million-ton increase is much larger than the 850,000 tons the industry added to its newsprint-making capacity during the past 10 years.

On the average, manufacturers of all types of paper plant to boost their capacity by about 6.2 million tons during 1980, 1981 and 1982 -- an annual rate of increase of about 2.9 percent.

According to the institute survey, the U.S. paper industry had record production of 6.47 million tons of paper and paperboard in 1979, a 5 percent increase over 1978.

Furthermore, according to the institute's president, Louis F. Laun, demandd for paper and paper products remains high. Whatever situation the rest of the economy may be in, the "paper and paperboard industry shows little evidence of recession," he said. Orders for paper products remain high and backlogs of unfilled orders also are high.

Laun cited a number of factors, besides the rise in newspaper advertising, that benefited the paper industry in 1979, including:

A five percent increase in magazine advertising pages last year.

A continued rapid increase in the introduction of new magazines.

A generally modest level of inventories of packaged goods, which means that manufacturers will not stop producing suddenly. Continued production will keep up demand for paperboard products used in packaging goods. p

The paper institute said that the industry spent $4.8 billion to expand, modernize and clean up pollution from paper mills last year.

Luan said that if the economy goes into a tailspin as projected , the paper industry should suffer no more than the average and may do better if imports of paper products decline. Last year the nation consumed about 5 million tons more of paper than American producers made.