The Scottish Government has outlined plans for a deposit return scheme for plastic drinking containers, cans and glass.

Environment Secretary Roseanna Cunningham told MSPs at Holyrood a "return to retail" model would be adopted and could be up and running by 2021.

Ms Cunningham said the deposit would be set at 20p as part of the government's climate action plan.

It means Scotland will become the first part of the UK to introduce such a scheme, which aims to capture 90% of drinks containers for recycling within three years.

In her statement to MSPs, Ms Cunningham said the scheme will apply to PET plastic bottles - for example fizzy drinks and water bottles - glass bottles and steel/aluminium drinks cans.

She also detailed her decision not to include high density polyethylene (HDPE) plastic - primarily used for packaging fresh milk - in the scheme, due to concerns over potential contamination of other materials and odour.

Ms Cunningham said HDPE could be added at a later stage if such concerns are addressed.

She said: "Scotland was the first part of the UK to commit to a deposit return scheme as part of our wider efforts to prevent discarded drinks containers from ending up in our streets and seas, and is now the first to outline its design - one that is ambitious in scale and scope, and which gives the people of Scotland a clear and straightforward way to do their bit for the environment.

"There is a global climate emergency and people across Scotland have been calling, rightly, for more ambition to tackle it and safeguard our planet for future generations.

"I am therefore delighted to confirm that I intend to implement a system covering PET - the most common form of plastic packaging - aluminium and steel cans, and glass, with a deposit refund set at 20p.

"Supported by international evidence our plans for Scotland's Deposit Return Scheme are gathering pace with widespread consensus demonstrating that a well-run, appropriately-targeted scheme could improve the environment, change attitudes to recycling and litter, and support a more circular economy."

Jill Farrell, chief operating officer at Zero Waste Scotland, said: "This will be a game-changer for recycling and the circular economy in Scotland.

"By giving people an extra incentive to do something good for our environment, and having a consistent approach across Scotland, we are confident it will be easier for all of us to do the right thing.

"This will improve the volume and quality of recycling and help tackle litter in the process."

Scottish Tory MSP Maurice Golden said: "A deposit return scheme can be a valuable tool in increasing recycling rates but is commonly used in advance of kerbside recycling infrastructure roll-out.

"Nevertheless, I recognise that the SNP government has been working on this scheme for over a decade and so I expect the smoothest possible roll-out."

Scottish Liberal Democrat energy spokesman Liam McArthur said introducing the scheme is the right thing to do in order to end the country's throwaway culture.

He said: "As we iron out the details it is essential that there are no unintended consequences.

"Island and rural areas must be properly accounted for, and we need to be certain that the inclusion of glass won't cause manufacturers to turn to more harmful materials.

"The next step must be moving urgently to tackle the mountain of coffee cup waste through a latte levy, preventing millions of cups going straight to landfill."