An eight-day hearing in March will consider the project’s plans to take over 250 hectares of common land. Although those backing the scheme, including Blaenau Gwent council, have pledged around 320 hectares to replace it, opponents remain concerned over the environmental impact of the scheme.

Construction had been due to begin next month, but the instigation of the public inquiry will put back the start date of the project.

The deal, which has been described as a hybrid PPP, was signed between the Heads of the Valleys Development Company and Blaenau Gwent council back in October 2013.

Contractor FCC, plus local firm Alun Griffiths, were tasked with undertaking preparatory work on the site, with development originally scheduled to begin soon after