US President Donald Trump is “open-minded” about policies and might be persuaded on foreign aid, Microsoft founder Bill Gates has said in an exclusive interview with the Guardian.

The billionaire philanthropist said President Trump does not have a fixed ideology in most areas and is open to new ideas, “particularly if it’s doing things in a different way than was done before”.

He added that Trump had already been influenced by arguments put forward by US defence secretary Jim Mattis, who emphasised the importance of soft power.

Gates was speaking ahead of Tuesday’s launch of the Bill & Melinda Gates Foundation’s annual Goalkeepers report, which warns that decades of progress in the fight against poverty and disease is at risk of stalling.

The report, which analysed progress made towards the UN’s sustainable development goals, said populations were growing fastest in the poorest parts of the world. Africa’s birthrate could prove an asset, but only if the world invested in the continent’s young people, it said.