The gas pipeline, part of a €900 million (£620 million) project to bring fuel from a gasfield 80 kilometres off the coast of Co Mayo to an onshore processing facility, has been dogged by controversy, including the arrest of five local men protesting against the pipeline.

“What I’m ordering them to do now is to undo the length of pipeline they welded,” he said.

Shell’s work on the project is also to be subject to more rigorous surveillance by government inspectors. “What we will have is authorised officers who will be able to go on site of any of the Shell works during the remainder of this project. They will be able to do so unannounced and without any prior notice,” the minister said.

Shell said yesterday that it believed that consent had been granted. “The company has been meticulous in complying with consents. As far as we are concerned consents were in place,” a spokesman said. However, the company said it had stopped welding until the matter had been resolved.

The regulatory confusion adds to Shell’s difficulties in Ireland, where a small group of protesters have doggedly opposed the laying of two kilometres of the steel pipe across their land. Known as the Rossport Five, the men have acquired the status of local heroes after being jailed for contempt of court for continuing to block Shell’s diggers in defiance of a court injunction.

Shell has announced that 91 jobs will be lost at the construction site because of the delays.