MURCO Milford Haven refinery has apologised after a lightning strike sparked problems which sent thick black smoke soaring into the sky.

From late afternoon on Tuesday, large plumes of smoke and flames poured from three refinery flare stacks at the site near Herbrandston.

At the time much of Pembrokeshire was experiencing heavy, thundery showers and electrical storms.

A Murco spokesman said that at around 3pm lightning struck Western Power Distribution equipment “resulting in a significant power dip that affected Milford Haven industries, including the Murco Milford Haven Refinery.

“The lightning caused a process interruption which resulted in a short period of flaring from the site. We have taken action to remedy the problems associated with the interruption and apologise for any inconvenience that this may have caused.”

The company said it is working closely “with the external authorities regarding this and is committed to ensuring the health and safety of its employees, neighbours and the local environment at all times.”

One concerned onlooker told the Milford Mercury: “It is always worrying when that much smoke is coming from a refinery and with the atmospheric conditions the smoke, which was really black, remained low.”

The flare was visible until 5pm. Several people on social networking site Twitter mentioned seeing black smoke from many miles away.

Western Power Distribution confirmed the lightning strike but said no equipment was damaged and domestic customers were not affected.

The Environment Agency said it was aware of the situation yesterday (Wednesday).