A natural gas leak has been ruled as the cause of a manhole explosion in Dublin city centre this morning.

No one was hurt in the explosion, which occurred at the corner of Merrion and Baggot Streets, near Government buildings.

John Morrin, who was working at nearby café Lolly and Cooks this morning, said before the explosion the manhole cover emitted thick green smoke that was “toxic-smelling”.

The café windows had to be closed because of the fumes. He said the smoke thickened and turned black before the manhole cover flew off.

Crews from the ESB, Bord Gais, Eircom and Dublin Fire Brigade have been working all day to determine the cause of the blast. A section of Merrion Street has been closed to facilitate the investigation.

A spokeswoman for Bord Gais Networks confirmed the incident was not gas related. She said: “Our crew is no longer present at the incident site. However, a fitter remains at the location assisting the ESB with their ongoing work.”

Traffic lights at the intersection and several local businesses are still without power.

ESB investigators now have access to the site of the explosion, which gardaí had blocked off due to the possibility of a gas leak. Now that a leak has been ruled out, investigators will be able to find the portion of ESB cable causing the power outage.

Eircom is no longer involved in the investigation. An Eircom spokesman said there is no damage to the telecommunications infrastructure. The company had not been working on its telecom cables anywhere near the intersection either before or at the time of the explosion.

Dublin Fire Brigade district officer David Kavanagh said the explosion is not believed to be heat related.