Momentum, the youth climate strikers and Extinction Rebellion are to unite in protest outside parliament on Wednesday as Labour calls on the Conservatives to declare an environmental emergency in a parliamentary vote.

A coalition of activists and campaigners will rally in Parliament Square to demand the government backs the plan, first put forward by Extinction Rebellion as the primary demand of the protests that engulfed London over the past fortnight.

Last month Labour declared an environment and climate emergency and the shadow environment secretary, Sue Hayman, challenged her government counterpart, Michael Gove, to follow suit. The party has now forced a Commons vote on the issue as concerns over pollution and climate change dominate the political agenda.

Momentum said climate change was caused not by ordinary people but by elites, and Labour was right to push the government to recognise the urgency and scale of the impending environmental crisis.

“It’s disgraceful that Theresa May has sat on her hands, refused to meet the climate strikers and ignored the huge public outcry about the climate crisis,” said Laura Parker, a Momentum spokesperson. “Climate change isn’t caused by ordinary people. It’s caused by elite politicians, oil executives and bankers who all profit from causing climate breakdown.”

She added: “Only Labour can challenge this climate-wrecking elite and deliver a green industrial revolution, which will mitigate climate breakdown whilst transforming our economy and society in the interests of the many, not the few.”

The protests follows school strikes in dozens of countries, mass demonstrations in London organised by Extinction Rebellion and the targeting by Momentum of banks that fund fossil fuel companies.

The leftwing grassroots movement has previously organised demonstrations outside parliament, such as in 2015 to put pressure on MPs to vote against the bombing of Syria in 2015, and to display support for the Labour leader, Jeremy Corbyn, after a number of shadow cabinet resignations in 2016.

Extinction Rebellion representatives are to meet the London mayor, Sadiq Khan, and the shadow chancellor, John McDonnell, on Tuesday and Gove on Wednesday.

The group is also calling for the government to act immediately to halve biodiversity loss and reduce net greenhouse gas emissions to zero by 2025, and to create a citizens’ assembly to spearhead reforms.