The vehicle was used to systematically flatten 500 metres of perimeter fence around the Langenstein-Zwieberge site.
It also rammed into the main gate leading to 13 kilometres of underground galleries dug by inmates in the final months of WWII at a huge cost in lives.
The bulldozer was driven 1.5 kilometres across fields at night to reach the memorial site and was later dumped and set on fire. Police estimated the total amount of damage at €50,000.
A political motive was not immediately suspected, however, since the intruders left the memorial signs and information boards intact, the Mitteldeutsche Zeitung reported.
There were also no graffiti inscriptions that often characterize pre-meditated attacks on sites connected with the Holocaust.
The Langenstein-Zwieberge site was a sub-camp of the Buchenwald concentration camp.
More than 7,000 prisoners from 23 countries were imprisoned there between April 1944 and April 1945 while they dug underground galleries for the concealment of industrial production.
An estimated 2,000 of the workers died of exhaustion, illness or brutality. At least as many died during a so-called death march evacuation of the camp in April 1945.
The site was preserved as a memorial in 1949 and opened as a museum in 1976.
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Last month thieves broke into the former Dachau concentration camp near Munich and stole the iron gate from the main entrance.
Bearing the infamous Nazi exhortation "Arbeit macht Frei" (Work will set you free), the gate is still missing despite a €3,000 reward posted for information leading to its recovery.
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