Cairo - Egypt's president again accused unknown parties of being responsible for the 2016 murder of Italian researcher Giulio Regeni, alleging a failed plot to sabotage bilateral relations during a Wednesday ceremony inaugurating a massive gas project with Italian energy firm Eni.The offshore Zohr field, discovered by Eni in 2015 and touted as the largest ever in the Mediterranean, began production last month after being brought online in record time despite the temporary cutting of diplomatic ties over the Regeni affair. It contains enough gas to eventually allow Egypt to cover its own needs and export the fuel.Speaking at the ceremony in Port Said, President Abdel-Fattah al-Sisi thanked Eni and the Italian government for persevering. Italy had withdrawn its ambassador in April 2016, saying Egypt was not cooperating in the Regeni investigation. An ambassador returned last September."We will not forget Italy's standing alongside us despite the Regeni case," al-Sisi said, addressing Eni CEO Claudio Descalzi by his first name. "Do you now know why they wanted to undermine relations between Egypt and Italy? So we don't get to be here," he added.Al-Sisi also repeated his pledge that Egypt would help bring the killers of the 28-year-old researcher to justice, and that his family in Italy should know that "we will not forget this incident, until we find the culprits and bring them to account."KEEP UPDATED on the latest news from around the continent by subscribing to our FREE newsletter, Hello Africa.FOLLOW News24 Africa on Twitter and Facebook. Regeni was a Cambridge University doctoral student researching labor movements in Egypt when he was abducted in Cairo in 2016. His body was found along a road several days later bearing marks of extensive torture, of the kind that activists and rights groups say is widespread within Egyptian detention facilities.Egypt's security services have denied any involvement in his abduction or death.In a letter published on January 25, the second anniversary of Regeni's disappearance, Rome prosecutor Giuseppe Pignatone said the motive behind the killing was "the research activity Giulio conducted in the months of his stay in Cairo," and that he had been under police surveillance until his disappearance.Regeni had been researching labor movements in Egypt, a sensitive subject that would have drawn scrutiny from security agencies. He went missing in central Cairo when police were out in force to prevent protests on the fifth anniversary of the 2011 uprising. His main contact in the unofficial street vendors' union later said he had told police Regeni was a spy.Egypt has been waging a fierce crackdown on dissent since the military overthrow of an elected but divisive Islamist president in 2013. Thousands of people have been jailed, mainly Islamists but also several prominent secular activists. Pro-government media routinely portray Egypt as the target of foreign conspiracies aimed at destabilizing the country.