According to Premium Times, the blast levelled the facility, popularly known as Isoko House, hours after the union began its annual conference there.

Witnesses believe the incident was a coordinated attack.

As at the time of filing this report, no group has claimed responsibility for the blast, and no casualties have been recorded.

The oil-rich Niger Delta region has witnessed several attacks in the past seven months, as separate militant groups bomb oil installations on weekly basis.

ALSO READ: Tanker explosion kills scores of people in Edo State

The Niger Delta Avengers, who recently announced a temporary ceasefire, claimed responsibility for most of the attacks on oil facilities.