© Reuters /Christian Mang"Letzte Generation" (Last Generation) activists cut the top of a Christmas tree at Brandenburg Gate, in Berlin, Germany, December 21, 2022.
Two women from campaign group "Last Generation" used a mechanical platform to ascend to the top of the 15-metre (49-foot) tree and sawed off a two-metre section.
A banner attached to the platform read: "This is only the tip of the Christmas tree."
Brandishing the sawn-off section, activist Lilli Gomez said: "In Germany, we are so far only seeing the tip of the underlying disaster.
"While all of Germany is spending the week getting the best presents from the biggest shops, others are wondering where they will get water to drink, after droughts and floods destroyed their crops."
She called on the government to do more to avert a looming "climate collapse."
A Berlin police spokeswoman said that three activists had been detained, and were being investigated for damaging property.
Climate campaigners in Germany have been stepping up protests in recent weeks, blockading motorways, major city roads and airports, and gluing themselves to famous paintings in museums.
Last week, investigators raided the homes of several activists belonging to "Last Generation", accusing them of backing a "criminal association".
Chancellor Olaf Scholz has also criticised them, saying in November that action such as the blockade of Berlin airport was "not only incomprehensible, but also highly dangerous".
"Those involved should consider activities other than those that are accepted by almost no one in Germany," he added.
Comment: It is little wonder that the soulless ideology of climate change would drive adherents toward destroying a cultural symbol of good will toward others.