Most German companies are finding it difficult to replace imports from Russia, Ukraine and Belarus, a survey showed on Tuesday, as Russia's war on Ukraine weighs on supply chains.

Only 13.8% of industrial companies reporting delivery problems from Russia, Ukraine and Belarus said they could completely replace their supply sources in the short term, the survey by the Ifo economic institute showed.

Some 43.4% said it was only partially possible to find other supplying sources and 13.8% said replacing these imports was not possible at all, the survey showed.

"Changing sources of supply causes headaches for many companies," Ifo economist Klaus Wohlrabe said in a statement, adding that there was often uncertainty as to whether and to what extent companies may be affected by sanctions imposed on Russia for invading Ukraine.

"Supply chains and production processes that have been tried and tested for years often cannot be reorganized at short notice," he adds.

(Reporting by Riham Alkousaa Editing by Paul Carrel)