The Scottish Government has ditched a flagship climate change commitment to ban landfill waste in Scotland by the end of 2021.
Environment Secretary Roseanna Cunningham has pushed the plan back by four years after admitting that councils and commercial operators were not ready.
Opposition parties are now calling on ministers to "set out in detail" how the plan will be met by 2025 in line with with new target.
Over 1 million tonnes of biodegradable waste is still finding its way into Scottish landfill, new figures revealed this week. It could have cost councils £1 billion over a ten--year period to export rubbish south of the border to comply with the ban, research earlier this year revealed.
Ms Cunningham insisted that "significant progress" had been made to meeting the ban in 2021 with most councils having "solutions in place," in a Holyrood written answer.
But the minister added: "The evidence available suggests that full compliance by 2021 will not be possible without reliance on export options, including landfill in England, with consequent environmental impact and additional financial implications for local authorities."
She went on: "I am prepared to accept – reluctantly - that a transitional approach is necessary; and that some commercial operators and a minority of local authorities need longer to achieve full compliance with the ban.
"Therefore, I have agreed that full enforcement should be delayed until 2025 for both public and private sectors managing wastes covered by the ban."
It comes after the Committee on Climate Change reinforced the importance of reducing reliance on landfill in recent advice.
Liberal Democrat leader Willie Rennie said: “The Scottish Government have binned their plan to introduce a ban on waste going to landfill by 2021.
“All along they haven’t had a coherent, coordinated policy and only when Liberal Democrats raised the issue did they start to admit they had problems.
“The Government must set out in detail how it will meet the new 2025 target, without resorting to filling lorries with waste and sending them south of the border.”