BERLIN (Reuters) - Germany's leading economic institutes have revised up their 2016 growth forecast for Europe's largest economy to 1.9 percent from 1.6 percent, several sources familiar with a report due to be presented to the government told Reuters on Wednesday.

The institutes revised down their estimate for 2017 growth to 1.4 percent from their previous forecast of 1.5 percent, the sources said.

The German economy expanded by 1.7 percent last year.

The institutes are due to publish their report on the outlook for the economy on Thursday. The institutes' forecasts form the basis for the government's own predictions.

(Reporting by Rene Wagner and Klaus Lauer; Writing by Joseph Nasr; Editing by Michelle Martin)