The UK has been warned not to send a dreadful message to the rest of the world by backing a controversial Australian former minister with a much-criticised climate change record to run the Organisation for Economic Co-operation and Development. The race to be the next secretary-general of the OECD – the Paris-based economic thinktank that advises governments across the world – has narrowed to Mathias Cormann, the former Australian finance minister, and Cecilia Malmström, the former EU trade commissioner and Swedish centrist politician. The result is due by 15 March. Malmström said she had the backing of many EU and non-EU countries in the 39-strong OECD, but admitted she did not know how the US, viewed as the key to the outcome, was planning to vote. Canada, also seen as critical, is likely to follow the US’ lead. John Kerry, Biden’s climate change envoy, was in London for talks with British ministers, and Labour’s shadow environment spokesman, Matthew Pennycook, warned it would send a terrible signal if it was known that the UK was backing Cormann. There have been strong suggestions from within the OECD secretariat that Boris Johnson told the Australian prime minister, Scott Morrison, in a call on 27 October that Cormann had the UK’s backing. The UK insists it has taken a strictly neutral position since the British ambassador to the OECD is acting as the neutral chair of the selection process. But Pennycook said it is imperative that the organisation is led by someone who grasps the urgency of the climate crisis. Michael Bloss, the German Green MEP, also questioned the UK’s judgment. “Acting on the climate crisis and economic cooperation must go hand in hand. The UK’s proposal to appoint Mathias Cormann is adding fuel to the fire and unnecessarily prolonging the fossil fuel era. Cormann is being directly supported by climate delayer and Australia’s prime minister, Scott Morrison. All our alarm bells should be ringing,” he said. The former US ambassador to the EU, Anthony Gardner, has also backed Malmström and warned the US not to back a candidate with a poor record on climate change, saying such a decision would be regrettable. The bulk of the 39 nations in the OECD are in the European Union, and it is thought Portugal, as current presidents of the EU, is working hard to ensure that she wins the support of most member states. But Cormann, once seen as an outsider, has pushed his way through the field and worked hard to distance himself from the climate change record of the government that he helped lead. Last week international climate change groups and advisers on the global shift from fossil fuels wrote to the OECD expressing “grave concerns” about Cormann’s leadership bid. Cormann’s role as Australia’s finance minister between 2013 and 2020 made it “highly unlikely” he could play an effective role in advocating for ambitious action on cutting emissions, the letter said. Cormann had been in a government that abolished a carbon pricing scheme, persistently failed to take effective action to cut emissions and “acted as a blocker with international forums”. The OECD needed to be a leader in tackling climate change, but Cormann had been part of efforts to thwart action, the letter said. Poland, one of the countries most hostile to the EU’s green policies, has been in talks with the Australians about the posting. Malmström said she would work strategically over her five-year mandate to see that targets were set to increase the number of women in the OECD in higher posts. She added gender needed to be part of any Covid recovery plan since women have suffered more during the pandemic. Cormann, who is Belgian born, has presented himself as a candidate who could rally support from across the world, including the increasingly influential Indo-Pacific.