The opposition BJP on Sunday retained the Dhamnagar assembly seat of Odisha in a bypoll, defeating the ruling BJD by a margin of 9,881 votes, an Election Commission official said.

The bypoll was necessitated by the death of BJP MLA Bishnu Charan Sethi in September.

Sethi's son Suryabanshi Suraj, who was the party's candidate, secured 80,351 votes, while BJD's Abanti Das bagged 70,470 votes, the official said.

Congress nominee Baba Harekrushna Sethi got only 3,561 votes.