International companies working on Saudi Arabia's $500bn Neom megacity, which has forcibly displaced members of the Howeitat tribe, have ignored requests to explain how they assessed the risks to human rights posed by their participation.

Out of a dozen firms, only three responded this month when UK-based NGO, the Business and Human Rights Resource Centre, asked them to set out what due diligence they undertook before signing on.

Keller Group Plc, McKinsey & Company and Air Products sent one-page statements, outlining codes of conduct, positions on human rights violations, and commitments to ethical business.

Rights monitors following the project said that the silence from most companies was disappointing, adding that the three firms that did respond offered replies that were too vague to offer reassurance that human rights concerns were being taken seriously...