"The widest approach would be best,I think. I would hope that in 10 years that most countries in the world would have signed up to it."
Malmstrom said carbon borderswould be a major structural reform and risked stoking trade tensions if not handled in a co-ordinated way.
"That's why you have to approach it very carefully and as broadly as possible – to make sure this is something that could potentially be beneficial to the whole world. I know there are lots of other countries starting to think about this."
Candidates for the secretary-general position have completed the first round of interviews and those with the least support will soon be eliminated. A winner will be chosen by March.
Malmstrom was the EU trade commissioner between 2014 and 2019 and spent four years before that as the commissioner for home affairs. If selected she would be the organisation's first female leader.
"As we come out of the immediate COVID crisis,we have to not forget there is an ongoing crisis which is the climate crisis,"she said.
"What the OECD can do is to show how to link economy and ecology. This should be one of the most important priorities of the OECD. Any secretary-general,whoever is elected,will have to spend a lot of his or her time on this."
Malmstrom also urged countries tohold their nerve and not unilaterally impose taxes on international behemoths such as Google,Facebook,Apple and Amazon before a global agreement is struck at the OECD in mid-2021.
France has become impatient with the OECD process and last month demanded hundreds of millions in euros from American tech firms for the 2020 tax year.
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A breakthrough at the OECD could reap up to $135 billion per year in extra revenue for 137 governments.
"With a joint effort there could be a solution ready by the summer and I think it's really worth waiting for,"Malmstrom said."If we can get nearly 140 countries to agree on something that would really be historic and set a new standard.
"I would encourage everybody to give it the time needed. It's a bit like the carbon border issue – if many countries start to go out on their own we risk complicating the matter."
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The OECD emerged from the post-war Marshall Plan and plays a key role in shaping the economic agenda. Its 38 members represent more than 60 per cent of global GDP.
Europe has not held the secretary-general position since 1996 and believes this contest is its chance to grab it back.
Cormann — who was born in Belgium,spent 25 years in Europe before migrating to Australia in 1996 and is fluent in German,French and Flemish — is pitching himself as a bridge between Europe's traditional economies and the increasingly important Asia-Pacific markets.