The Central Election Commission voided results in the 38th Nizami constituency in the northwestern city of Ganca. Election officials said local police interfered in the voting process.
Today's decision means the total loss of five parliamentary seats for the ruling Yeni Azerbaycan (New Azerbaijan) party. Yeni Azerbaycan now holds 58 of the 125 seats in the National Assembly.
Azerbaijan's political opposition claims the 6 November election was fraudulent and wants new polls to be held.
Hundreds of opposition supporters today demonstrated in the northwestern city of Zaqatala to demand that the results of the election be voided in two constituencies.
President Ilham Aliyev yesterday dismissed Zaqatala district-administration head Vaqif Rahimov for alleged interference in the vote.