Keir Starmer's swansong on the global stage faces being gatecrashed by his successor as Nato officials demand to know where Andy Burnham stands on defence.

The would-be Prime Minister has so far been vague on how he plans to keep the country safe and what he would do over the black hole in military funding.

And so, the Mail has learnt, Nato members gathering in Turkey next month have asked he be represented, even though it would be before the Labour leadership contest has officially opened.

The July 7 meeting is set to be Sir Keir's last hurrah as leader and was earmarked as the deadline for the PM to finally publish the long overdue Defence Investment Plan (DIP).

However, the timetable for Mr Burnham's coronation has potentially pushed the report's publication back by several more months.

Mr Burnham is close to Al Carns, the former Armed Forces Minister who warned the DIP and related Strategic Defence Review, are out of date. The ex-Royal Marine, who has specialist knowledge of the conflict in Ukraine, may convince Mr Burnham a further delay is necessary to make corrections.

Mr Carns quit over the direction of the DIP this month, hours after Defence Secretary John Healey resigned over the money on the table, just £10billion in real terms.

Military chiefs warn that £28billion is needed just to stand still, let alone reach the target of 3.5 per cent of gross domestic product to be spent on defence by 2035.

Despite announcing his departure, Sir Keir remains entitled to announce big decisions, so could keep his previous promises to find extra money for defence – then leave his successor to fund it.

But he may face opposition from senior government officials.

On Monday, Scottish Secretary Douglas Alexander refused to say whether the DIP would be published before the Nato summit.

Conservative leader Kemi Badenoch said delivering the DIP was a 'very urgent' priority that mustn't be held up by Labour succession plans. She said: 'What we don't need is Starmer's farewell tour or Burnham going on holiday. Not funding a Defence Investment Plan is a national security issue.'

Sir Keir's claim in Monday's resignation speech that he 'restored trust' in defence was mocked after fallout over the DIP, giving away the Chagos Islands – thereby threatening the future of the Diego Garcia airbase in the Pacific – and facilitating the continued persecution of veterans of the Troubles in Northern Ireland.

Former Army intelligence officer Philip Ingram said: 'Starmer did not restore an ounce of trust. He set the conditions for the resignations of his Defence Secretary and his Armed Forces Minister.

'He tried to push through a deal on a sovereign territory, the Chagos Islands, for a political ego trip and oversaw our veterans being hounded in the courts in Northern Ireland while pandering to the terrorists. While he inherited the rot in our Armed Forces, he spread disinformation about investing more. He damaged our influence with our most important ally, the US. Simply, Starmer's tenure as PM has made our country less safe and less secure.'

Former Royal Navy commander Tom Sharpe accused Sir Keir of widening the gap between what is promised and what is delivered.

He accused Sir Keir of 'bringing in other items' to the budget 'to show an increase'. Sharpe added: 'Even when Healey and Carns resigned the automated response from Starmer was "nothing to see here". Ultimately, he lacked the leadership and conviction to control the Treasury sufficiently.'