United Nations, May 3: UN Secretary General Antonio Guterres has urged Donald Trump not to walk away from an international deal designed to prevent Iran acquiring nuclear weapons.Speaking to the BBC, Guterres said there was a real risk of war if the 2015 agreement was not preserved.Trump has been a strong critic of the accord, in which Iran agreed to limit its nuclear programme in return for the lifting of sanctions.The US president has until May 12, to decide whether to stick with the deal.Guterres told the BBC that the Iran agreement was an "important diplomatic victory" and should be maintained."We should not scrap it unless we have a good alternative," he said, adding: "We face dangerous times."It comes just days after Israel revealed "secret nuclear files" accusing Iran of having covertly pursued nuclear weapons.US Secretary of State Mike Pompeo said the files provided proof that the Obama-era nuclear deal was "built on lies", the BBc report said.European allies France, the UK and Germany meanwhile have agreed that pursuing the current nuclear deal with Iran is the best way to stop it developing nuclear weapons.In 2015, Tehran signed a deal with the US, China, Russia, Germany, France and Britain agreeing to limit its nuclear activities in return for the lifting of crippling economic sanctions.Under the deal, officially known as the Joint Comprehensive Plan of Action (JCPOA), Iran is committed to slashing the number of its centrifuges, which are machines used to enrich uranium.It is also meant to cut its stockpile of enriched uranium drastically and not enrich remaining uranium to the level needed to produce nuclear weapons.Trump has frequently voiced his opposition to the "insane" deal, which he has described as the "worst ever". Unless the European signatories to the deal and the US Congress addressed his concerns he plans to withdraw on the next deadline for waiving sanctions. Trump is unhappy that the deal only limited Iran's nuclear activities for a fixed period (till 2025) and had failed to stop the development of ballistic missiles.He also said it had handed Iran a $100bn windfall that it used "as a slush fund for weapons, terror, and oppression" across the Middle East.Iranian President Hassan Rouhani has questioned the legitimacy of efforts by the US and France to change the nuclear deal with his country.He has said that Iran "will not accept any restrictions beyond its commitments" to comply with international rules in the years ahead.