THE man who allegedly murdered Labour MP Jo Cox had links to far-right organisations in Britain and the US — where he bought bomb and home-made gun building manuals, it was claimed yesterday.

A civil rights organisation based in Alabama in the US has published a receipt which it says proves that 17 years ago Thomas Mair, now 52 years old, bought the manuals from the National Alliance (NA), which was once the US’s leading neonazi organisation.

The Southern Poverty Law Centre (SPLC) produced the document bearing Mair’s name and address in Batley, West Yorkshire — in Ms Cox’s constituency.

He spent $630 (£440) on the manuals, according to the receipt, issued by NA’s publishing arm National Vanguard Books.

His purchases included the Chemistry of Powder and Explosives, Incendiaries, the Improvised Munitions Handbook — and instructions for making a “pipe pistol for .38 caliber ammunition.”

Mair has also been reported as being a subscriber to SA Patriot, a South African pro-apartheid magazine published by the extremist White Rhino Club.

Ms Cox was a campaigner against racism, supported migrants and was in favour of Britain remaining in the European Union.

Mair, who allegedly fatally shot and stabbed Ms Cox in the street in her Batley and Spen constituency, reportedly shouted: “Britain First” or “put Britain first” repeatedly as he carried out the attack.

Sheffield Trade Union Council (TUC) said it was of “great concern” that Mair allegedly shouted “Britain First.”

“The police investigation must take its course but we urgently need to know if this was a political assassination by a far-right extremist and whether Jo was targeted for these views,” said Sheffield TUC in a statement. 

A joint statement by Unite Against Fascism secretaries and Stand up to Racism co-conveners Sabby Dhalu and Weyman Bennett said: “Batley and Spen has a history of fascist and racist activity. 

“Six years ago Terrance Gavan, who was linked to the BNP, was sentenced to 11 years in prison after 54 explosive devices were found in his home in Batley.

“There is no doubt that Jo Cox was targeted because of her positive views on immigration, her humanitarian work helping refugees and her excellent relations with the local Muslim community.”

Mair’s house was sealed off by police yesterday, who were guarding the property as forensic officers worked in the garden.

Downing Street said that the Conservatives will not stand a candidate in the by-election, which will now take place following her death.