CAIRO (AP) — Egypt's president has again accused unknown parties of being behind the 2016 murder of an Italian researcher, alleging a plot to sabotage bilateral relations during a ceremony marking the start of a massive gas project with Italian energy firm Eni.

President Abdel-Fattah el-Sissi spoke during the Wednesday ceremony in Port Said to inaugurate the offshore Zohr field, touted as the largest ever in the Mediterranean.

Thanking Eni CEO Claudio Descalzi directly, el-Sissi said: "Do you now know why they wanted to undermine relations between Egypt and Italy? So we don't get to be here." He pledged Egypt would help bring the killers of the 28-year-old researcher to justice.

Rome prosecutor Giuseppe Pignatone wrote in a recent letter that Egyptian secret services had a role in Regeni's abduction, torture and killing.