A build up of toxic smoke in a sewer underneath the street was the cause of a manhole cover to blow open in Dublin City yesterday.

The blast was witnessed by up to a dozen passers-by at the corner of Merrion St and Baggot St at approximately 10am. There were no injuries.

Emergency services were informed and the street was closed for a number of hours as crews from the ESB, Bord Gis, Eircom and Dublin Fire Brigade attempted to discover the cause of the blast.

Initial fears were that the explosion was gas related but Bord Gais have confirmed that it was not.