Campaigners have raised concerns about nuclear warheads travelling through Northampton after a convoy passed an accident-prone stretch of motorway.
Nuclear warheads are regularly driven from Burghfield Atomic Weapons Establishment (AWE) near Reading to Coulport, Scotland, for loading onto the Trident missile submarines.
On Tuesday, a 20-vehicle convoy was spotted heading north passing close to Bicester on the M40 before nearing Brackley and Towcester on the A43 and, shortly afterwards, navigating the Northampton stretch of the M1.
But the campaign group Nukewatch say that if the lorries carrying the weapons were involved in a major crash, a fire could cause radioactive contamination over a wide area.
Though a minor incident, the convoy on Tuesday was delayed near Didcot, Oxfordshire, after a breakdown. Last year a warhead-carrying lorry broke down on the slip-road at junction 9 of the M40.
Nukewatch’s Nigel Day described the convoy as "probably the most deadly cargo in the country" and said the campaign group has serious concerns about it travelling along the accident-prone stretch between junction 15 and 16 of the M1 and the A43.
"What we are saying is that this is a particularly dangerous convoy and there is a possibility of an accident because these things happen all the time on these roads," he said.
"When the convoy travels along, cars often travel in and out of it - in that respect, it is quite dangerous."
Sometimes, though not always, the convoy is flanked by police vehicles and a rolling roadblock is put in place.
A Ministry of Defence (MoD) spokesman said: “For security reasons, MOD does not discuss the purpose of specific convoy movements.”