A further consideration is the cost – between £80,000 and £100,000 for each scanner. A major airport would need to have several, to avoid huge delays.

So far, the DfT has only "encouraged" airports to adopt the scanners, although it has the power to order them into line, if necessary.

But a spokesman for Peel Airports Group, which owns JLA, insisted there was only the "potential" for the scanners to be introduced.

He added: "We are awaiting clarification from the DfT over the potential use of body scanners and so are unable to comment as to whether John Lennon Airport will see such machines being installed."

The scanners are already in place at Heathrow and Manchester airports, and will be installed at Birmingham's by the end of February.

Once they are installed, it will be compulsory for the "small proportion" of passengers selected for a scan to take part, or they will not be allowed to fly.

A DfT spokesman said: "We are encouraging airports to install these scanners, which clearly bring security benefits.”

JLA is already at loggerheads with the Government over rising air passenger duty – prompting Lord Adonis to accuse it of “whingeing”.