Keir Starmer has warned his likely successor, Andy Burnham, that it will not be possible to spend less time focusing on international affairs.

Speaking during a BBC interview, he also spoke of his “intensely personal” decision to announce his resignation last month after two years as prime minister.

Throughout his premiership, the Labour leader has faced accusations of spending too much time on the world stage instead of domestic affairs, with his opponents calling him “never here Keir”.

Burnham has largely focused on domestic issues as he sets out his stall to be the next prime minister.

But Starmer warned that the future prime minister would not be able to spend less time grappling with the turmoil around the world than he has.

He told the BBC: “If you’re prime minister and you care what bills are going to be like in any household around the country, you have to care about finding a lasting solution to the situation in Ukraine, you have to care about what happens in the strait of Hormuz.

“It’s not sensible to think you can just separate these two things out.”

Asked if he believed it was possible for his successor to spend less time on diplomacy, he said: “No, I don’t think it is possible. So this suggestion you can really, in the modern era, simply split up the international and domestic, is just … it just doesn’t make sense.

“It isn’t true. It isn’t right.”

Starmer also spoke about how he came to the decision to resign after spending a weekend with his family at Chequers, the grace-and-favour Buckinghamshire country estate available to all prime ministers.

He said: “For me, and this may be different for other people, in the end it became an intensely personal decision, and that’s why it was a decision taken ultimately when Vic and I were away with the kids, we went to Chequers and just spent two days together as a family, and that’s when I came to my final decision.”

Starmer also said he believed he had “saved” the Labour party and had been a successful prime minister, adding he promised to “keep my mouth shut” under his successor.

Burnham earlier gave some indication of how he may govern in the realm of foreign policy when he took part in an “Ask Me Anything” session on the forum website Reddit.

The Makerfield MP said he would “100%” give the same level of support to Ukraine as Starmer had and suggested he wanted to continue with the outgoing prime minister’s efforts to broker a closer relationship with the EU.