Egypt's public prosecutor Wednesday cleared five policemen of responsibility in the murder of Italian student Giulio Regeni and said he will not pursue the case because the perpetrator is unknown.

The decision announced by state prosecutor Hamada al-Sawy comes nearly three weeks after Italian prosecutors said they planned to charge four Egyptian security officers over the torture and death of Regeni.

The Cambridge University graduate was in Egypt researching trade unions, when he was kidnapped in January 2016 and his mutilated body later found on the outskirts of Cairo.

His death sparked outrage in Italy and strained diplomatic relations between the two countries, with Italy's government accusing Egyptian authorities of non-cooperation.

Sawy in a statement published Wednesday said Egypt's public prosecution has no intention of "pursuing a criminal case in the murder, abduction and torture of Giulio Regeni because the perpetrator is unknown".

Investigators would continue to seek the identity of the murderer but the prosecution has "ruled out" any charges "against the four officers and a fifth policeman" in connection with the case, he said.

Amnesty International activists hold a picture of student Giulio Regeni who was murdered in Egypt as they take part in a demonstration in front of the Italian Parliament in Rome in January 2017 a year after his killing
Amnesty International activists hold a picture of student Giulio Regeni who was murdered in Egypt as they take part in a demonstration in front of the Italian Parliament in Rome in January 2017 a year after his killing AFP / ANDREAS SOLARO

On December 10, Italian public prosecutor Michele Prestipino told a parliamentary commission in Rome there were "elements of significant proof" implicating Egyptian policemen.

"We are going to ask to begin a criminal action concerning certain members of the Egyptian security services," he said.

"We owe it to the memory of Giulio Regeni," he added.

Regeni had been researching the sensitive topic of labour organisations in Egypt when he disappeared. He had also written articles critical of the government under a pen name.

Since his death, Italian investigators have rejected multiple theories put forward by Egyptian authorities, including that Regeni had been working as a spy, or that he was the victim of a criminal gang.

Late last month, Egypt said it would "temporarily close" its parallel investigation into Regeni's murder, saying Rome's accusations were based on insufficient evidence.

Egypt