A general debate is scheduled to take place today to mark 50 years of Operation Relentless, which sees the Royal Navy carry nuclear weapons to sea from HMNB Clyde.

HMS Resolution conducted the first patrol in June 1968 and continuous patrols began in April 1969

SNP defence spokesman Stewart McDonald MP said he would use the debate to highlight “the dangers of Trident renewal” to domestic and international security, making the case for investment in conventional defence measures.

A trident submarine makes its way out from HMNB Clyde in 2009. The UK's continuous at sea deterrent has now been in operation for 50 years. Picture: Getty

Nationalists have consistently opposed renewal of Trident nuclear weapons, which the party claims could cost up to £200 billion over their lifetime.

Mr McDonald MP said: “In the middle of such an enormous constitutional crisis it is obscure and somewhat perverse for Westminster to indulge itself in a self-congratulatory debate about being a nuclear power for fifty years.

“Quite simply, there is no military or economic case for the renewal of trident. The iron-clad consensus that exists between the Tory and Labour front benches on the issue of Trident remains one of the UK’s greatest weak spots and continues to endanger millions.

“The billions spent on Trident continues to suck up money from conventional defence and security – which has always been the priority of the Scottish National Party – and completely ignores the new and evolving threat picture the we in the UK face to which nuclear weapons cannot meet.

“Just a few days ago Parliament’s Public Accounts Committee admonished Tory and Labour Westminster Governments for their eye-wateringly expensive mishandling of nuclear submarine decommissioning, with an estimated £7.5billion bill. This ought to be the subject of a public inquiry, not a back slapping love-in dressed up as a debate.”

SNP dismiss Commons debate on nuclear deterrent as ‘back slapping love-in’