A former first minister of Northern Ireland has accused Scottish Nationalists of "doing violence" to people's identity with their bid to take the country out of the United Kingdom.
Lord Trimble said that every Scot had a "British component" in their national identity, and that to "separate that is to do violence to people's own sense of identity".
The politician, who won a Nobel Prize for his efforts in the Northern Ireland peace process, spoke out at a rally for the Union at the Scottish Conservative conference in Troon in Ayrshire.
Tory politicians from all four countries in the United Kingdom joined together to make the case for Scotland staying in the Union.
Lord Trimble argued that there was a "common component" in the national identity of people from all parts of the UK.
And he stated: "I have to say to Scottish Nationalists that by fighting for a programme of separatism, saying that you want to take Scotland out and take the Scottish identity out into a separate place, you are doing violence to part of the identity of every Scotsman, because there is a British component in the identity of every Scotsman.
"And to separate that is to do violence to people's own sense of identity."
Lord Trimble said people in Northern Ireland were "concerned about what is happening" in Scotland, with the SNP administration planning on holding a referendum on independence in autumn 2014.
He said Northern Ireland had "come out of a huge campaign that was intended to break the Union".
But he said that had failed because of the efforts of the police and the armed forces, but also because "we won the political argument".
Lord Trimble, former leader of the Ulster Unionist Party and now a Conservative peer, told the conference: "That political argument was crucial. And the argument we put to the people of Northern Ireland was all about the benefits of being in the United Kingdom, of how by being part of a larger unit our own particular difficulties could be more easily reconciled."
He said that just as the case for staying in the UK had been made successfully in Northern Ireland, the same could happen in Scotland.
Lord Trimble said: "We have a situation just across the water from here where the argument has been won and the number of voters supporting Nationalism is declining significantly.
"Just as we have won the argument there we can win the argument here again also."
Lord Strathclyde, Leader of the House of Lords and also leader of the Tory group in the Lords, was another of the politicians who spoke out as the Conservative Friends of the Union group was officially launched at the conference.
He claimed that Scotland, "the country I care passionately about most of all in this world", was "under threat".
He said: "Because of the vanity-driven egotistical policies of the SNP, Scotland stands on the brink of breaking up the most precious and successful political and economic co-operation the world has ever seen - the United Kingdom."
Lord Strathclyde insisted that "Scotland's ambition is best served by our full participation in this extraordinary partnership that has lasted for over 300 years".
And he said: "When the referendum comes, let us ensure that Scotland says no to division and yes to our United Kingdom."
Conservative Party chairman Baroness Sayeeda Warsi said the Tories must "work flat out" to keep the Union together.
She said Scottish First Minister Alex Salmond had been "banging the drum for division" but added: "It's our job to drown out his separatist rhetoric with a positive case for keeping the Union intact."
She said the Tories must make a positive case for Scotland staying in the United Kingdom, arguing: "This campaign needs to be not just about Scotland being worse off without the rest of the UK but about how Scotland is better off in the UK and the UK is better off when we are united.
"In voting to save the Union we are voting for stability, for strength and prosperity."
Welsh Secretary Cheryl Gillan said the union between the four countries that make up the UK provided "strength, security, freedom, prosperity".
She added: "With economic uncertainty around the world, now is not the time to prise the Union apart."
Ms Gillan went on: "The people of Wales know they are better off in Britain and I think the people of Scotland will know they're better off in Britain too."
Meanwhile, Scottish Tory leader Ruth Davidson stressed the importance of the independence vote.
"The next thousand days could determine the future of the country we love for the next thousand years," she said.
"It is that important. The next thousand days could decide which passport we hold, which currency we spend, which army protects us. It is that important."
Ms Davidson added: "This is a big decision - it's not like an election where you can change your mind five years later.
"The decision we make here and now could change the face of our country forever."
SNP MSP Humza Yousaf said later that Lord Trimble "appears to know as little about modern Scottish identity as David Cameron does".
He added: "This is exactly what David Cameron and Ruth Davidson didn't want - their much promised positive case for the Union hasn't even survived the Tory launch event, and now lies in tatters. It is precisely this sort of negative nonsense that is so damaging to the Tory-led anti-independence campaign.
"Lord Trimble couldn't be more wrong about Scotland.
"Independence is the broad, inclusive and positive option for Scotland, in which the wide range of identities we have in our modern nation - Scottish, British, Pakistani, Chinese, Polish, Irish and many, many more - can all be reflected and celebrated."