Borrowers in the international money markets will have little difficulty getting bank loans in the months ahead, even if their credit ratings are something less than "prime."

But bankers will offer longer repayment terms instead of lower interest rates - a trend officials worry about but seem helpless to contest.

In part the so-called "ease" in money market conditions is due to sluggish loan demand for business expansion in the major industrial countries - an outlook for which there seems to be little prospect of improvement.

These are among the main conclusions of a new survey of international capital markets published today in the International Monetary Fund monthly survey.

It is based on discussions by a team of IMF staff members during March in eight major world money capitals, and with officials of banks and international organizations. Nevertheless, the report said the assessment of future lending trends should be considered "highly tentative."

According to the analysis, although a lengthening of maturities "is viewed as increasing somewhat the margin risk to the banks, more emphasis is given to the shorter-run impact of a decline in spreads on bank earnings.

The report said maturities on new Euro-currency loans began to stretch out after the highly publicized failures of the West German Herstatt Bankhaus and the American Franklin National Bank in 1975. Thus, in 1977, 77 percent of Euro-currency loans were five years and over, compared with only 33 percent in 1975 and 43 percent in 1976.

And by the first quarter of this year, 90 percent of new commitments had a maturity of five years or more, and 50 percent had a maturity of 10 years or more.

"Neither bankers nor regulatory authorities seem to feel comfortable with 10-year or 12-year lending by banks, yet many bankers appear to prefer making longer loans than accepting even lower spreads, and it seems likely that maturities will lengthen in the remainder of 1978," the survey said.

According to the report, total new international bank lending and bond financing in 1977 rose to $100 billion, up $4 billion from 1976. But allowing for inflation, the real volume declined by about 4 to 5 percent. This year's money flows are expected again to be around $100 million, meaning another dip a real terms.

The slowdown last year and this is a function of declining demand, not any inadequacy of supply of funds.

The report noted a significant decline in the rate of growth in foreign lending by American banks, compared with others in Europe, Canada and Japan. This was traced to acceleration of domestic loan demand in the United States last year.

Despite the lengthening in Euro-currency maturities, the report also notes that as much as 60 percent of U.S. banks' outstanding international claims are short-term - that is, with time remaining to maturity of less than one year.