KONTAN.CO.ID - JAKARTA. On Wednesday, a blast rocked an optics and optical electronics factory in the town of Sergiev Posad, 50 km (30 miles) northeast of Moscow, injuring at least 45 people, local authorities said.

Emergency services said the blast appeared to have occurred in a warehouse containing pyrotechnic equipment, the state news agency TASS reported. The popular online news channel Mash said it had been rented by a pyrotechnics firm.

Twenty-three people were admitted to hospital, including six in intensive care, the Sergiev Posad mayor's office said.

Unverified footage on social media showed a massive column of smoke and high-rise buildings with windows blown out.

The Zagorsk Optical and Mechanical Plant produces optical equipment for industrial and healthcare applications as well as for the Russian security forces.

However, TASS cited emergency services as saying they did not believe the blast had been caused by a Ukrainian drone attack - many of which have occurred in Moscow and the surrounding area in recent weeks and months.

Editor: Syamsul Azhar