The SNP must set out its plans for income tax in Scotland before next year's Holyrood elections, David Mundell has said.

The Scottish Secretary said Nicola Sturgeon's party must stop its "constant gripes" about "detail and process" and "tell us straight" how it plans to use new devolved income tax powers.

Mr Mundell said he wanted to implement the new powers in 2017 so the parties contesting next year's Scottish Parliament election would have to go into the poll with a clear plan for income tax.

He told the Conservative Party conference in Manchester: "Because we know that the new tax powers are at the heart of the devolution package in the Scotland Bill, we want them to come on-stream as soon as possible.

"I would like that to be in 2017.

"The final date for the transfer will be agreed between both of Scotland's governments as part of the fiscal framework negotiations, which are on-going.

"But we think 2017 is an achievable and desirable time for these new powers to take effect.

"It would mean that the Scottish Government elected next year would have to include plans for these new powers in its first budget so when people in Scotland go to the polls next year, the parties will need to present their plans for income tax.

"And they'll need to be honest about what they will mean for Scottish taxpayers.

"The Scottish Conservatives have been clear - under us, Scots will never pay more tax than our neighbours in the rest of the UK."

Meanwhile, leader of the Scottish Conservatives Ruth Davidson called on her party to be "visionary" and strive to achieve "old fashioned blue collar Toryism".

Ms Davidson told the conference: "I don't want us to be just the party of the technocrat. The grudging vote of competence.

"I want us to be the party of the thinkers, the dreamers, the reformers and the visionaries too.

"The zeal of the missionary, the courage of the pioneer, the ambition to lift our eyes to the horizon and say there's a new Jerusalem we want to build and we will work towards it every day."