Two serving ministers have called for a “much greater pace” of investment in defence spending, putting pressure on Rishi Sunak a day after the Commons’ spending watchdog warned that the Ministry of Defence had no credible plan to fund the military capabilities the government wants. The Foreign Office minister Anne-Marie Trevelyan and Home Office minister Tom Tugendhat said in a post on LinkedIn that the UK needed to “lead the way” by increasing defence and security spending to at least 2.5% of gross domestic product, a measure of the size of the economy. The chancellor, Jeremy Hunt, has said “our spending will rise to 2.5% as soon as economic conditions allow” – surpassing the Nato-wide target of 2% – but provided no details of how that would happen. “The sad truth is that the world is no longer benign,” Trevelyan and Tugendhat wrote. “Protecting ourselves requires investment. And effective investment means that our industrial complex must grow and strengthen at much greater pace than at present.” The article was not required to be cleared by No 10 because it was a social media post. It was also in line with government policy on increasing spending to 2.5%. But the article by the senior Tories signals unease within the ranks over defence spending – an unease reflected in the findings of the public accounts committee. On Friday, the committee published a report calling for the government to get firmer control of defence procurement, noting that the defence ministry had become “increasingly reliant on the UK’s allies to protect our national interests”. The report found that the gap between the defence ministry’s budget and the cost of the UK’s desired military capabilities had increased to £16.9bn – its largest deficit to date – but the committee warned that the real deficit could be closer to £29bn. “In an increasingly volatile world, the Ministry of Defence’s lack of a credible plan to deliver fully funded military capability as desired by government leaves us in an alarming place,” said Dame Meg Hillier, the chair of the committee. In response to the report, a No 10 spokesperson told the PA news agency: “The prime minister has overseen the largest sustained defence spending increase since the end of the cold war and a £24bn uplift in cash terms over the spending review period. “We are ensuring that we have the largest defence budget in history, increasing spend and ensuring that we have the funding that we need to protect UK national interests.” In their article, Trevelyan, the Indo-Pacific minister, and security minister Tugendhat said they were concerned about the level of defence spending needed to respond to China, which announced this week that it was increasing its defence spending by another 7.2%, and Russia, which has committed to spending 40% of its expenditure on defence – much of that in Ukraine. “It’s clear to us that the UK needs to lead the way in increasing our own domestic defence and security spending commitments to 2.5% and beyond,” they wrote. “Former defence secretary Ben Wallace and prime minister Boris Johnson made inroads into growing our defence budgets, which had been shrinking in real terms for years. But that only filled the hole. Now we need growth.” They called for an investment in defence and security industry, a strengthening of the UK’s nuclear deterrent and a growing of the country’s munitions lines, in part to help bolster the efforts in Ukraine. “We cannot turn on the complex platforms and weapons which ensure military advantage overnight,” they wrote. “We must start that growth now, invest at pace to support our allies and stay ahead of our adversaries.”