Egypt's president Abdel al-Fattah al-Sisi on Wednesday vowed his country would help "unravel the mystery" surrounding the murder of Italian student Giulio Regeni, who was found tortured to death in Cairo last month.
"I wish to underline the importance of strengthening cooperation between our two countries to unravel the mystery surrounding this death and to bring the killers to justice," Sisi told Italian daily La Repubblica.
The 28-year-old Cambridge PhD student's slaying had been "a terrible shock for Egypt as it was for Italy," Sisi said, calling the murder "terrible and unacceptable".
"The Italian people can rest assured that our efforts will continue day and night until we find out the truth about what happened, arrest those responsible and deliver justice," Sisi stated.
But he questioned the timing of the murder of Regeni, who vanished in Cairo on 25 January and was allegedly found dead in a ditch on the western outskirts of the capital on 3 February with signs of torture.
"Why did this happen during the visit to Egypt of an Italian business delegation headed by the economic development minister, which was in Cairo to boost bilateral ties?" he said.
Upon learning of Regeni's murder, Italy's economic development minister Federica Guidi cut short her visit to Egypt.
"Why did this occur at a time when political and economic ties between our countries had reached unprecedented levels?" Sisi said.
"We should not forget how important this cooperation is at a time when the Egyptian economy in crisis and has been weak for years," he added.
Regeni's murder and the collapse of Russian investments in Egypt since the downing of a tourist jet in Sinai last year were "retaliation for Egypt's major war on extremism and terrorism," Sisi claimed.
"The objective is to damage the Egyptian economy and to isolate the country," the former army chief concluded.
The joint investigation into Regeni's abduction and murder has been put under the direct oversight of Egypt's prosecutor general Nabil Ahmed Sadek, Rome prosecutors said on Tuesday after meeting him in Cairo.
The Italian government has publicly criticised Egypt's lack of progress in the Regeni probe, over which seven Italian police officers were sent to Cairo last month.
Cairo has rejected suspicions by many in Italy and elsewhere that Egyptian security forces killed Regeni and has denied he was a spy. It has said criminal motives, 'revenge' or terrorism could lie behind the murder but has so far made no arrests in the case.
Regeni disappeared amid an unprecedented security clampdown on the fifth anniversary of the uprising that ousted Egypt's former strongman Hosni Mubarak.
He was researching trade union activism in Egypt - a sensitive topic - and had published articles critical of the government and the lack of democracy in the North African country.