Scottish Labour leader Kezia Dugdale will insist her party can offer a "radical challenge" to the SNP with just 100 days until polling begins in the Holyrood elections.

Ms Dugdale will be in London to brief the UK shadow cabinet on the May 5 Holyrood vote, days after a new poll painted a bleak picture of her party's prospects.

The Panelbase poll for The Sunday Times and Heart FM indicated the Scottish Conservatives are gaining ground in the fight to be Scotland's second largest party, with Labour dropping to 21% in the constituency vote.

Ms Dugdale remained upbeat ahead of meeting UK party colleagues, highlighting her plans to use new powers over tax coming to Holyrood to fund investment in schools.

She said: "Shadow Cabinet members will be left in no doubt that we will run a confident and positive campaign based on our ideas to transform Scotland.

"We are going to make a radical challenge to the SNP about how we use the new powers to break from Tory cuts.

"Scottish Labour thinks education is a priority so we would ask the richest few earning more than £150,000 a year to pay a bit more in tax to invest in our schools.

"The SNP say education is a priority but are cutting half a billion pounds from local council budgets for things like childcare and schools.

"The First Minister said she wanted to fight this election on the SNP's record in government. That is exactly what we will do. Our public services are suffering under the SNP, with school standards slipping and cuts being proposed in our NHS.

"Labour can be the authentic voice for those who are desperate for change. We will go into this election with confidence in our vision for Scotland."

The weekend poll put support for the Scottish Greens on 3% in the constituency vote, and 5% in the regional.

Co-convener Patrick Harvie MSP said the party was preparing to distribute half a million newspapers across Scotland in a bid to capitalise on positive polling.

He said: "With 100 days to go our top team of candidates and local branches around the country are gearing up for our biggest and best campaign to date.

"With our increased resources we're determined to make the most of positive polling which shows the chance we have to make a real breakthrough.

"In 100 days Scotland will elect the Parliament which will serve till 2021, and we can't afford to see critical issues ignored till then.

"From scrapping the council tax to taking the action needed to abolish fuel poverty, and from investing in the jobs of the future to finally meeting the country's climate change targets, it's clear that Green influence is needed like never before."