PM warned that attempts to prevent conflict will be harmed by cuts to overseas aid

Former spymasters, military chiefs and leading politicians are among a group of more than 60 public figures to sign a letter urging the prime minister to allocate more of the UK's reduced overseas aid budget to preventing wars.

A failure to act risks leaving the government facing what they described as a "global conflict crisis" with "one hand tied behind its back". The letter to Sir Keir Starmer, shared with Sky News, said violent conflict is impacting more countries across the globe than at any time since the Second World War.

"They are disrupting economies and diverting the world's attention away from human rights, climate change and gender equality," according to the letter, signed by, among others, Baroness Eliza Manningham-Buller and Lord Jonathan Evans, former director generals of MI5, and Lord Mark Sedwill, a former national security adviser. "To durably strengthen national security, therefore, the government must invest not just in defence, but also in development and diplomacy." The group is not calling on the prime minister to reverse a decision to shrink the overseas aid budget to 0.3% of GDP from 0.5% by 2027 to fund an increase in defence spending.

Instead, they are focused on the proportion of the diminished international development budget that is spent on conflict prevention and peacebuilding. The ratio had been 4% of total overseas aid spending in 2018.

But the level has shrunk to between 1 and 1.5% today, according to Lord Jack McConnell, co-chair of the All Party Parliamentary Group on Conflict Prevention, Conflict Resolution and Peacebuilding, which organised the letter. The group wants the proportion to be returned to the equivalent of 4%.

"Without this, the UK might risk facing the global conflict crisis with one hand tied behind its back," the letter warned. The signatories said they would like to see an all-of-government approach to tackling violent conflict to be included in an upcoming national security strategy, which is due to be published before a NATO summit next week.

Read more from Sky News:Charities attack foreign aid cutListen: 'War ready' - but for what war?Defence review numbers checked Among the other people to sign the letter are General Lord Richard Dannatt, a former head of the army, Air Chief Marshal Sir Michael Wigston KCB, a former head of the Royal Air Force, Tan Dhesi MP, chair of the defence select committee, and Sarah Champion MP, chair of the international development committee. Conflict prevention and resolution efforts that the UK has in the past championed include helping to secure peace agreements in the Philippines, Colombia and Ethiopia.

Another initiative is the "Women, Peace and Security" agenda. "We are gravely concerned that these initiatives may disappear amidst cuts to the aid budget," the letter said.

"This would be a false economy, as conflicts left to escalate and spread will lead to further insecurity, forced displacement and humanitarian crises to which the armed forces and aid agencies must respond.".