Germany and Kazakhstan signed agreements Wednesday worth three billion euros ($4 billion) to cooperate on raw materials, industry and technology, Berlin said.

The raft of some 50 accords was inked during a visit to the German capital by long-time Kazakh President Nursultan Nazarbayev, the German economics ministry said without giving details.

"There's a big interest by German companies to invest more in Kazakhstan," German Chancellor Angela Merkel said after talks with the Kazakh leader, adding that trade ties could be further improved.

Trade between Germany and Kazakhstan jumped 20 percent last year to 6.3 billion euros, according to figures from the Federation of German Industry, which welcomed the partnership accords.

The Central Asian nation, rich in natural resources, is already an important supplier of oil to Germany and also possesses rare earths vital for everything from iPods to missiles.