The magnetoelectric properties of a rhombohedrally distorted perovskite BiFe0.7Mn0.3O3 are reported. An anomaly in the dielectric constant. related to enhanced thermal fluctuations around the antiferromagnetic transition, was induced near room temperature by the substitution of Mn for Fe in BiFeO3. This substitution also brings about non-trivial magnetocapacitance effects at room temperature. (c) 2005 Published by Elsevier Ltd.