Boris Johnson was asked whether he was worried when Mr Sunak initially said he wouldn't be attending the conference in Egypt due to preparations for the UK government's Budget on 17 November.
Mr Johnson replied: "The prime minister's here. I'm glad he's here. He's made an outstanding speech the other day. He's on absolutely the right lines."
He added that he attended the conference as a "foot soldier and spear carrier of the Conservative Party, purely in a supportive role to remind the world of what we did in Glasgow".