World airlines belonging to the International Air Transport Association agreed yesterday on increases in international passenger fares ranging from 5 to 10 percent to offset rising jet fuel costs.

The increases, which vary depending on route, direction and fare category, will be effective April 1 if they are approved by the governments involved.

Announcing the fare agreements at a news conference following the close of the meeting in Geneva, IATA spokesman David Kyd said increases averaging 10 percent would be sought by the airlines for routes between the United States and Europe, but that carriers were free to add or subtract 2 percent "according to discretion."

IATA member airlines also agreed on increases in international cargo rates ranging from 6 to 13 percent, effective March 1.

The only U.S. airline to take part in the week-long discussions was Flying Tiger, a cargo carrier. Most U.S. airlines have dropped out of IATA over the last few years and have submitted fare proposals to the Civil Aeronautics Board that are outside the IATA rate structure.

In that connection, the CAB met yesterday in secret to discuss international fare increases ranging from 3.5 to 8 percent proposed by Braniff International, Pan American World Airways and Trans World Airlines, to be effective next month.