Burglars have broken into the house of former German foreign minister Hans-Dietrich Genscher and stole the pen he used to sign the country's unification treaty in 1990, media reported Wednesday.
"This loss is very painful for me," Genscher told daily Bild.
The thieves reportedly used a crowbar to prise open the fortified glass windows to Genscher's home in the former German capital Bonn, while the 84-year-old statesman was out to dinner with his wife, Barbara.
The pen was stolen along with other historically valuable fountain pens and some of Barbara Genscher's jewellery, Bild reported.
The couple contacted the police after the burglary, on March 11, but they were unable to trace the thieves or the stolen goods.
"I am very attached to these things. They are irreplaceable and form part of my professional life," the former minister said.
The 1990 treaty, signed by the four Allied victors of World War II as well as East and West Germany, ended the country's division and created one Germany on October 3, 1990.