The pastor for the church in Schweringen informed officials on Thursday that he had discovered the Nazi symbol engraved on the bell was removed, according to the Lutheran church's branch in the area.
It said a note claiming responsibility was also found, but did not give details.
Local newspaper Die Harke published a picture of a note, which read "spring cleaning 2018".
The church suspended use of the bell last year after the swastika was found.
Local church officials recently decided to put it back in use - a decision that was contested by the pastor.
The church said on Tuesday it will now consider how to proceed and whether to take any legal action.
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