Relaxed, smiling and in a gregarious mood, former U.S. budget director Bert Lance told European executives here today that a balanced U.S. budget by 1981 was still possible if the economy grows at a 5 per cent rate and the administration pursues a tight spending policy next year.

Speaking at a Conference Board luncheon on his first trip abroad since he resigned. Lance claimed the Carter administration would try to impose a budget ceiling in fiscal 1979 of $498.6 billion. The package would yield a real spending rise of little more than one per cent, one of the smallest increments in a decade.

The 1979 budget deficit would be "significantly lower" than the 1978 shortfall of $63 billion. Lance added.

At a press conference preceding his address. Lance downplayed the current friction between Carter and Congress, noting. "Any new administration faces a time of trial and testing with Congress before action on key issues takes place."

Acclaimed by many businessmen as their most influential voice within Carter's inner circle. Lance said he did not believe his resignation would cause the administration to fall "out of touch with the American business community."

Turning to the plunging dollar that has hurt European export drives. Lance said he felt the U.S. Treasury would step in to halt the slide "only when necessary, but I don't think right now is appropriate."