A senior Plaid Cymru peer has apologised for "any offence caused" after comparing the effects of a Trident submarine base to those of a Nazi death camp.

Lord Wigley had been commenting on reports - denied by the Government - that the nuclear weapons system could be relocated from Scotland to Wales.

Speaking the day after the world marked 70 years since the end of the Holocaust, the peer made clear that Plaid would be "tremendously opposed" to shifting the base from Faslane naval base to Pembrokeshire.

Asked whether the move would have some positive benefits, such as bringing jobs to the area, Lord Wigley - a former leader of the party - replied: "Look, this week we have been remembering what happened in Germany before the war, no doubt there were many jobs provided in Auschwitz and places like that but that didn't justify their existence and neither does nuclear weapons justify having them in Pembrokeshire."

Challenged as to why he was comparing a Trident base to the notorious death camp, he replied: "The number of people that will be killed by Trident will be infinitely more."

In a statement released later, Lord Wigley said: "I am certainly sorry if my remarks were open to any misinterpretation and I apologise for any offence that has been caused.

"The point I was trying to make was that you can't have jobs at any cost and I reiterate that."

Former Welsh secretary David Jones branded Lord Wigley's comments "crass", and said he was right to offer an apology - albeit a "mealy-mouthed" one.

"His remarks were crass and defensive, and while the apology is a bit mealy-mouthed, at least it is good that he has acknowledged they are offensive," the Tory MP for Clwyd West said.

Mr Jones said it was "not appropriate at any time" to use Auschwitz to make political points.

"Nothing that ever happens in this country could ever be as appalling as what the Nazis did," he added. "But to say it at Holocaust memorial time is even worse."

Lord Wigley initially drew the comparison between Trident and a Nazi death camp in an untaped conversation, before repeating them in an interview for the BBC and the Press Association.

He said: "The point I'm making is that you have to look at what a job entails not just the fact that there is a job located in any particular area and, in this instance, we do not believe that we should have nuclear weapons at all, we believe that Trident shouldn't be renewed and we most certainly don't want that renewal to happen in Pembrokeshire or anywhere in Wales or, to be fair, anywhere in Britain.

Pressed on whether he was suggesting there was a "moral comparison" between working on a Trident base and working at a Nazi death camp, Lord Wigley said: "No, the point I was making was this, that you have to consider the nature of the work and not just that a job exists."

The remarks by Lord Wigley, Plaid's election co-ordinator, came after commemorations were held at Auschwitz to mark 70 years since its liberation.

Some 300 survivors returned the the site in Poland - where around 1.1 million people were killed between 1940 and 1945.

The SNP strongly opposes the renewal of Trident, but the UK Government has dismissed reports that the Ministry of Defence is making contingency plans for the weapons to be relocated from Scotland to Wales.

Prime Minister David Cameron's spokesman said: "There are no plans whatsoever. It is not on the table at all."

Scottish First Minister and SNP leader Nicola Sturgeon distanced herself from Lord Wigley's comments.

"It is not language I would use. It is not a comparison I would make," she said.

Scottish Secretary Alistair Carmichael said the comments were "offensive" and trivialised the Holocaust.

"I visited Auschwitz with a group of Scottish school kids on a Holocaust educational trip a few years ago and it's only when you visit the place that you understand the sheer scale of the horrors that were perpetuated there," he said.

"It's offensive to our servicemen and servicewomen who work there (at Faslane) - and that's bad enough. But it really is offensive towards the people who suffered and died in Auschwitz.

"It tells you a lot about the attitudes that you get from people whose judgment seems to go out of the window when a topic like this comes into play. It's not a rational position.

"The whole point is Auschwitz's place in history is because of the people who died there and not the people that worked there. And if you trivialise that - and that is trivialising it - then you increase the chances that something like that could happen again.

"There are some things that shouldn't be used in day-to-day politics and Holocaust memorial is one of them."

Former Liberal Democrat leader Sir Menzies Campbell said: "Dafydd Wigley has always been a passionate politician, but on this occasion he has gone too far.

"He should withdraw the comparison."