A sophisticated system aimed at protecting the UK from nuclear terrorism has not been activated because the Government is yet to sign a contract, Labour is to claim.
The scanners, designed to detect nuclear fissile material, have not been switched on, shadow immigration minister Chris Bryant will allege in a speech attacking the Government's efforts to secure the borders and tackle immigration.
He will warn that the failure to turn on the Cyclamen system is a "disaster waiting to happen" and the result of "chaos" in the way that measures to protect the borders have been procured by Theresa May and the Home Office.
"This is what guarantees protection from nuclear fissile material at our ports," he will say. "The kit is in place. The portals have been built. But they are not switched on because the Government still hasn't signed the contract. This is a disaster waiting to happen."
The annual report on the Government's Contest counter-terror strategy published in March said: "We have completed the major programme for the installation of equipment to detect and deter the illicit importation of radiological and nuclear material (known as Cyclamen).
"Fixed installations are supported by mobile radiation detection units that can be deployed to any location nationally and in support of police operations. We will continue to invest in maintaining and developing this capability to keep abreast of changes at the border and improvements in technology."
Elements of the Cyclamen system were deployed at the Olympics and an agreement was signed last year with France to install it at the Channel Tunnel terminal in Coquelles.
In a wide-ranging speech the Labour frontbencher will accuse ministers of using "gimmicks" such as the van encouraging illegal immigrants to go home, and propose new powers to tackle an "epidemic" of sham marriages. Mr Bryant will say that the way marriage law interacts with immigration is "not fit for purpose" and will propose the Home Office be given greater information and powers to investigate suspicious.
In the speech in Westminster Mr Bryant will say: "Registrars have told me that they are facing an 'epidemic' of sham marriages. Why? Partly because when you close down one route it is likely that people will use another. But also because the way marriage law interacts with immigration is simply not fit for purpose. Understandably, registrars do not see themselves as immigration officers. They see their job as facilitating marriage."
Mr Bryant said the Home Office should have real-time online notification of all notices of marriage where one or both people are under immigration control and for the notice period to be extended from 15 days to 20 or 25. Under his plan, if the Home Office detects any anomalies the period can be extended to 60 or 90 days, during which officials can do full and proper investigations and "if the marriage does prove to be sham the person under the immigration control would be removed".