Tories need to offer voters an alternative to the "poison" of independence in the referendum campaign, the leader of the Welsh Conservatives has said.

Andrew Davies, who leads the party in the Welsh National Assembly, claimed Nationalists in Wales are "driven by a binding, twisted hatred".

He went on to attack SNP leader Alex Salmond's campaign for Scottish independence, saying that the UK "cannot be allowed to slip through our fingers".

Mr Davies told the Scottish Conservative party conference in Stirling that his dealings with Plaid Cymru in Wales showed him that "what drives them forward isn't a coherent argument about independence but a binding, twisted hatred, a hatred for something that they just cannot accept".

He said: "I find that so, so heartbreaking, that people are driven by hate rather than what is good for the community, for the country they live in and, above all, for their fellow human beings."

People in Scotland are set to vote on the country's future in next year's independence referendum.

"What is needed in the independence debate is to make sure that we map out the bright, hopeful future that the 21st century holds for a United Kingdom, strong in its belief and purpose," Mr Davies told the conference.

"Ultimately what we have got to be driving is the alternative narrative to Alex Salmond's poison that is the independence argument.

"The United Kingdom cannot and must not be allowed to slip through our fingers. We need to preserve it for future generations so they can share in this oracle, respected for prosperity and security, that our generation and previous generations have enjoyed. We must not allow anyone to sleepwalk over the precipice."

SNP Westminster leader Angus Robertson hit out at the "abusive language" used by those campaigning for the Union.

Alistair Darling, chair of the Better Together cross-party campaign to keep Scotland in the UK, should apologise for using words like "poison", Mr Robertson said.

"Alistair Darling has got to take responsibility for this abusive language by senior supporters of the No campaign, and apologise for it.

"Mr Darling was sitting next to Lord Strathclyde on Wednesday evening when he clearly described Scottish independence as poison. And now the leader of the Tories in the Welsh Assembly has also described independence in identical terms.

"Mr Darling is speaking at the Tory conference tomorrow. He should take the opportunity to apologise for these remarks on behalf of the No campaign and tell his Tory friends to mind their language."