FRANKFURT (AFX) - The West German business climate index rose to 91.5 pct in May from 90.5 in April, and was up from 90.6 in May last year, the Ifo institute said. The May business assessment index was at 77.6, up from a revised 77.0 in April but down from 86.6 in May last year. The May business expectations index was at 106.1, up from a revised 104.7 in April and 94.7 in May last year. The AFX consensus forecast of economists was for the Ifo business climate index to fall to 89.7 in May. President of the Ifo Institute, Hans-Werner Sinn, said the improvement in the business climate index was driven above all by positive comments from surveyed manufacturing and wholesale businesses. In the retail and construction industries, however, the already cool climate worsened slightly, he said. In East Germany the business climate, after holding steady over the past three months, worsened slightly, Sinn said. This was due to negative comments from East German retailers and construction firms. Like their West German counterparts, East German manufacturers reported an improved business climate, he said.