The UK’s move to set a target to limit the amount of carbon dioxide emissions now faces a challenge after the country’s decision to leave the European Union.

Earlier in the week the UK agreed to set a legally binding aim of cutting the country’s carbon dioxide emissions to help with the climate change prevention effort.

However, a think tank led by Nigel Lawson, the former Tory Chancellor and strategy committee member of the Leave campaign, has dismissed the move as “unlawful”, which is indicative of the uncertainty triggered by the Brexit vote.

The Global Warming Policy Foundation fronted by Lord Lawson said the government was wrong to make a fifth ‘carbon budget’ a legally binding agreement that would see the UK commit to reducing emissions by 57% by 2032 compared with the levels of 1990.

The foundation said that the target was based on the false assumption that the country will still be in the EU in 2030.

Furthermore, they said that it also assumed that the UK would stay part of the EU emissions trading scheme, the biggest carbon market in the world, and would be “covered by the terms of the EU Paris agreement.”

Collectively, the EU has agreed to reduce carbon dioxide emissions by 40% by 2030 as part of December’s Paris agreement.

In a statement the foundation explained that it believes the government has behaved unreasonably and should have delayed the approval of the budget as well as reassessing the potential impact of a vote to leave the European Union.

They said that the government had “hastily rubber stamped” a budget that was only designed to work in one set of circumstances and as such it is “unlawful” and something that the incoming Prime Minister should review as a priority.

The UK’s 2008 Climate Change Act means that the government must set a budget every five years for the amount of CO2 that is to be emitted.