A huge political row was brewing this week as DEFRA appeared unable to commit to a compensation package for Scottish and Welsh farmers affected by the foot-and-mouth outbreak.

Farmers north of the border enduring sheep trade meltdown are now poised to take to the streets of London and Edinburgh if a comprehensive compensation package from the UK government is not announced within days.

"If we don't see signs from government at a UK level this week that a really meaningful, urgent and targeted compensation package is forthcoming we will have no option but to take our case to the streets," said Jim McLaren, NFU Scotland president.

The Scottish government is temporarily bankrolling a £5m-£6m welfare disposal scheme for light lambs aimed at averting an animal welfare catastrophe on Scotland's hills.

"Action is needed now and we will provide funding on an emergency interim basis and seek to recover this from DEFRA in due course," said Richard Lochhead, Scottish cabinet secretary for rural affairs.

But the minister was absolutely clear "the moral and financial responsibility for this crisis lies with the UK government".

About 250,000 hill lambs of up to 25kg liveweight will be eligible for the 10-week welfare scheme with farmers paid £15 a lamb.

Charles Milne, Scotland's chief veterinary officer, said the nominal payment was not compensation. "I don't think any farmers would choose to go into this scheme for economic reasons," he said.

"We were faced with a very stark choice - leaving these lambs on the hills to suffer or providing an alternative humane way of destroying them," Mr Milne added.

NFU Scotland reiterated the moral responsibility that the UK government had to compensate farmers, and has sent a letter to Prime Minister Gordon Brown demanding details of compensation for Scottish farmers.

NFUS president Jim McLaren added: "If the government fails to act, it risks presiding over the demise of much of Scotland's livestock sector."

The Farmers Union of Wales went on to claim its members had been "sold down the river" by the government's aid package for English farmers.

Gareth Vaughan, the union's president slammed DEFRA secretary Hilary Benn for ignoring the plight of Welsh and Scottish farmers when he presented details of the £12.5m allocated to English farmers.

Mr Vaughan insisted that, by concentrating on England, the minister had turned his back on the "polluter pays" principle, having already accepted that Pirbright was the "most likely" source of infection.

Without extra money, the £7.7m of aid offered by the Welsh Assembly to finance a light lamb welfare scheme and enhanced market promotion would have to be found from its existing agricultural budget.

Deputy FUW president Emyr Jones warned that Mr Benn's failure to extend central aid to Wales and Scotland would turn the simmering anger felt by farmers into outright fury, forcing them to take to the streets.

More than 300 lowland farmers voiced their anger at a rally in Ashford, Kent.