The Prime Minister has told Scotland's First Minister to call an independence referendum to end the constitutional uncertainty in the country.
Alex Salmond has previously stated that he wants to hold a referendum on the issue in the second half of this five-year parliamentary term, most likely in 2014 or 2015, after a "proper debate, consideration and a white paper".
His party, the Scottish National Party (SNP), won an unprecedented majority in the Holyrood election this year, meaning no opposition party can stand in the way of the referendum plan.
But David Cameron said that he should "get on" with asking the question to allow a "strong" United Kingdom to emerge.
Speaking at the Conservative Party conference in Manchester, Mr Cameron told BBC News: "If he's going to endlessly sort of militate and make things unstable in terms of Scotland's relationship with the United Kingdom then I think better to get on and put the question, find the answer and then I hope get on with building a strong United Kingdom."
A spokesman for the First Minister said: "A referendum in Scotland is clearly a matter for the Scottish Parliament and Government - and the referendum that is happening is the one the SNP pledged in the election campaign, which we said will be held in the second half of this parliament.
"That is the platform the SNP stood on in May, and which the people of Scotland gave us a resounding mandate to deliver.
"The immediate priority is getting economic teeth into the Scotland Bill, so that we can sustain Scotland's recovery, and not have it derailed by a Tory/Lib Dem government at Westminster which is cutting too far and too fast.
"Under the 'Plan MacB' being delivered by the SNP Government, employment in Scotland is rising and is higher than in the UK as a whole, and unemployment is falling and is lower than across the UK - indeed Scotland is the only part of the UK where unemployment is falling, which demolishes the Tories' scaremongering on the constitution."