A British woman died after being shot by her companion during a wild boar hunt in France on Sunday, in what a prosecutor described as a "dramatic accident".

The 67-year-old was wounded "above the heart" and taken to hospital in Saint-Brieuc, Brittany, where she died around midday, prosecutor Nicolas Heitz said.

Her 69-year-old companion was taken into custody and a manslaughter investigation has been launched. 

While the exact circumstances of the shooting were still to be established, tests on the shooter had already established that he not under the influence of alcohol or drugs, said Heitz.

The hunting party had been crossing a field in the Goudelin area, and included around a dozen hunters and two guests, the prosecutor said.