Labour leader challenges first minister's claim to centre-left politics, saying he is shutting the door on his fellow citizens

Ed Miliband has accused Alex Salmond of pursuing policies that will increase economic and social divisions within Britain by trying to split up the United Kingdom.

Speaking in Glasgow, the Labour leader singled out the first minister's claims last week that Scotland was a "progressive beacon" for the rest of the UK by implying that Salmond's form of nationalism was reactionary and divisive.

"There is nothing progressive about a brand of politics which is based on dividing people with the same needs, living on this same small island," Miliband said, in his first major speech on independence since Salmond set a referendum date for autumn 2014.

Claiming Salmond had no interest in the fate of pensioners in Liverpool, poor children in east London or a person with disabilities in the Midlands, Miliband continued: "That isn't a progressive vision: that is shutting the door on the problems of your fellow citizens."

As Miliband was delivering his speech, a coalition of Scottish civic and business leaders put Labour, the Tories and the Liberal Democrats under direct pressure to discuss whether Holyrood needed more radical powers on taxation, welfare and social policy.

Launching a non-party initiative in Edinburgh, senior figures in the voluntary sector, the Church of Scotland, the Scottish TUC, the Institute of Directors and the thinktank Reform Scotland said the pro-UK parties were ignoring the wishes of most Scottish voters by closing down the debate on whether Scotland needed greater autonomy by focusing solely on independence.

However, Salmond's hopes that this group would fight for devolution plus – or devo max – to be included as an extra option in the referendum were dashed by Alison Elliot, chair of the Scottish Council for Voluntary organisations, which has set up the Future of Scotland initiative.

She said its purpose was to "make the connection, so far lacking, with the issues that matter to people in this country. [It's] an adventure. If we knew what the outcome of this debate was going to be we wouldn't be holding it, but we do believe it is essential, if the referendum on Scotland's future is going to have any meaning and therefore any credibility."

Miliband is explicitly trying to challenge Salmond's attempts to position the Scottish National party as the champion of centre-left, socially-conscious politics in Britain, rather than Labour.

Pushing away questions about whether he would campaign jointly with David Cameron to oppose independence, Miliband said he planned to fight Salmond "toe to toe" on both independence and for leadership of the centre-left. The Labour leader insisted he was in favour of devolution to Scotland but said the current battle was solely over independence and Salmond's referendum in the autumn of 2014.

In the Hugo Young lecture last week for the Scott Trust, owners of the Guardian, Salmond said Scotland was upholding the founding principles of the British welfare state by defending universal benefits including free university education, free prescriptions and free care for the elderly.

By introducing the UK's first smoking ban and pushing for minimum pricing on alcohol, as well as a "social wage" for public sector workers, the Scottish parliament was pressing on with other progressive reforms while Labour, the Lib Dems and Tories were dismantling the welfare state through their spending cuts at Westminster, he said.

"An independent Scotland could be a beacon for progressive opinion south of the border and further afield," Salmond said, contributing more than "sending a tribute of Labour MPs to Westminster".

Miliband's speech is designed to answer critics who have repeatedly accused Labour and the other pro-UK parties of failing to set out a positive case for remaining in the UK. He and Scottish Labour leaders have come under intense pressure from the Tories and Lib Dems to take the leadership for the anti-independence parties, since Labour's political base in Scotland is much larger.

He did not directly attack Salmond's policies as first minister, but focused instead on making the case for the union. Attacking the philosophy of nationalism, Miliband said he believed Salmond was wrong to believe independence would help Scotland achieve more.

"What is the most urgent task facing us today? Putting up a border across the A1 and M74? Or the task of creating a more equal, just and fair society?" Miliband said.

"Of course, the Scottish people have always stood out for their strongest ideals of social justice," he added. "My case is that these ideals for Scotland can best be realised in the United Kingdom, and that the progressive ideals of the people of Scotland are more ambitious than Alex Salmond would claim."

Despite Salmond's claims that Scotland can best realise its egalitarian politics as an independent country, said Miliband, "Britain is united in its diversity, by shared values and common interests; not an island divided by borders on the basis of nationalities or nationalisms, but one brought together with the strength drawn from multiple identities; bound together by common ties."

He added: "When the Olympics are on [in July], nobody in the pubs in Newcastle will cheer any less loudly for Chris Hoy, wearing the Union flag, just because he was born in Edinburgh."

Miliband, who later accompanied Johann Lamont, the Scottish Labour leader, on a factory visit in Lanarkshire, is under pressure to increase his profile in Scotland, particularly in the runup to the local government elections in May, which will prove to be another critical test of Labour's popularity. The SNP insists Miliband is less popular in Scotland than in any other part of the UK.