The UK’s departure from the European convention on human rights would be catastrophic and is extremely unlikely, the development minister, Andrew Mitchell, has said as he launched plans designed to show that the UK is back as a global leader on development. His remarks put him at odds with those in the cabinet who have said they are prepared for the UK to leave the ECHR if it is necessary to push through plans to send refugees arriving in the UK on boats to countries such as Rwanda. Speaking at Chatham House, Mitchell said: “I don’t think there’s any question of Britain leaving the ECHR, the prime minister I think has made that pretty clear.” He said he accepted that the UK was willing to test the limits of what was possible under the ECHR, but added: “I think that leaving the ECHR is incredibly unlikely to happen. It was built by British ministers and British lawyers after the second world war. It is extremely important and you can imagine the effect of Britain withdrawing, what it would be on other countries with malign intent who would also feel they could withdraw. “It would be a huge thread pulled out of the international system, which is already on the back foot … with catastrophic effect.” He said the prime minister had drilled into the details and radically improved the relationship with France, a precondition of solving the boats issue. He said no democratic government could expect to get re-elected when people were coming across on boats “in an arbitrary and unstructured way”. He has previously said there are currently no safe routes for asylum seekers to come to the UK. In a wide-ranging speech setting a sharply different tone from some of his ministerial colleagues, Mitchell also described as appalling what was happening in the US to roll back women’s rights, a reference to the recent US supreme court judgment on abortion. He said: “It is a time when crises are everywhere but leadership is not, when we can save a bank in three days but Zambia waits for more than two years for debt relief, when our children can secure mortgage finance for 30 years but developing countries secure maturities in just over five years.” He said anger in the global south was rising as it saw “a developed world can invent quantitative easing to find money for themselves, but cannot find money to save the planet”. Mitchell said the government was minded to publish a development white paper designed to get the UK and the world back on track to meet the sustainable development goals (SDGs) for 2030. “We want a policy so that whoever wins the next general election, we have a programme that endures any change in government and which can deliver on the SDGs.” He said: “There will be an explosion of anger at the end of this year if there is no progress on this,” saying clear progress was needed on climate finance by the end of the year. “The white paper could incorporate the learning and expertise that Britain likes to champion.” He said the government was now spending 0.55% of gross national income on development, not far short of the government’s previous but currently renounced target of 0.7%. He said: “I know these cuts are painful for our partners and dented our reputation.” Britain’s development leadership “had been sorely missed across the world”, he admitted. At the same time, he pointed out that extra finance could be found by simple changes to capital adequacy reserve rules agreed at the spring World Bank meeting, a shift that released an extra $4bn a year. He said he did not believe any incoming government would want to break up the merger of the Foreign Office and the Department for International Development, saying the reaction of most people would be that they could not stomach any more structural change that would take more years to settle down. He said: “I am in the business of making the new structure work.” He said he wanted to boost public support for aid in the UK. Currently, only half of Britons support UK aid spending, but his objective is to make this rise to 70% within 10 years, as measured by a development engagement lab run by the University of London. “We must be honest and accept that we do not currently sufficiently enjoy support for our ambitious programme. I am determined we shall win over the doubters and drive up support.” Mitchell, who held the international development brief in the government led by David Cameron, said this would require taking the argument outside the capital. Mitchell accepted that 28% of the UK aid budget was being spent on housing refugees in the UK, and promised that in conjunction with the Treasury he was trying to bear down to secure value for money on this Home Office spending. He said that for the moment he had to “suck it up” but he was trying to make sure this diversion of aid spending was temporary. He said: “I know a lot of money is being spent on bedsits in Bedford and not in Africa,” but he added that this spending was legitimate under the OECD rules, and if he tried to change the rules he could open a Pandora’s box.