The Iranian regime remains the biggest threat to stability in the region 40 years after its revolution under ayatollah Ruhollah Khomeini, the Saudi ambassador to the US said. “Forty years ago, the Ayatollah landed in Iran and ushered a reign of terror and destruction,” Prince Khalid bin Salman said on Wednesday night on Twitter. Saudi Arabia, the UAE and their Gulf allies accuse Iran of funding armed groups that operate in Lebanon, Iraq, Syria and Yemen. Most of the Arab states believe that peace and stability in the Middle East cannot be achieved without confronting Tehran’s regime. “In Iran living standards declined, infrastructure stalled, and development froze,” Prince Khalid said. "The regime continues to waste its people’s money on deadly adventures abroad." Prince Khaled denounced Iranian President Hassan Rouhani's claim during revolution celebrations on Monday that Iran once controlled territory in the southern Arabian Gulf, saying. Mr Rouhani’s "dangerous and expansionist rhetoric is a reminder that this regime has not moderated, and represents the biggest threat to stability in our region,” Prince Khalid said. Prince Khalid’s comments come as foreign ministers and senior officials from 60 countries gathered in Warsaw for a conference on countering Iran’s influence and tackle regional challenges such as the wars in Yemen and Syria. The meeting is also expected to look at ways to curb Iran's missile programme. Saudi Arabia joined the conference “to take a firm stand against forces that threaten the future of peace and security in the region,” Prince Khalid said. “Especially the world's leading sponsor of terrorism: the Iranian regime that continues to destabilise our region and launch ballistic missiles against civilians,” he said. US peace envoy Jason Greenblatt hailed the event, saying “Iran’s aggression in the region has brought Israel and the Arab world closer together”. “Our talks today are important. But this conference cannot be the end. We need action beyond today,” Mr Greenblatt said on Twitter. “Syria. Yemen. Proliferation. The peace process. Terrorism. Iran. Cyber security. Humanitarian crises. None of the region’s challenges will solve themselves. We must work together for security,” he said.