MEMBERS of a gang suspected of being linked to the murder of an Italian student whose torture and death sparked an international outcry over possible police involvement have been killed in a gun battle with authorities.

The four men were killed inside their vehicle in an eastern Cairo suburb, Egypt's interior ministry said, adding that the group was suspected of orchestrating the kidnapping of foreigners and robbery. A body was found inside the group's vehicle next to weapons and forged police identification cards.

The gang members specialised in abducting the foreigners while posing as policemen and police found the personal belongings of Cambridge University student Giulio Regeni, 28, in a raid, the ministry said.

Mr Regeni went missing on January 25, the fifth anniversary of Egypt's 2011 uprising, when police were deployed across Cairo in a broad security sweep to prevent any demonstrations.

The interior ministry said police raided one of the gang member's houses and found the personal belongings of Mr Regeni, including his red bag bearing the picture of the Italian flag, his passport and other ID cards, including one belonging to Cambridge University, in addition to his mobile phones.

Italian officials have repeatedly complained about a lack of transparency from Cairo amid media speculation that Mr Regeni might have been a victim of the widespread torture and secret detentions by police that have been condemned by rights groups.

Mr Regeni had been in Egypt since September conducting research on workers and union rights - a sensitive topic, since disgruntled workers were among the forces in the 2011 anti-Mubarak uprising and authorities still worry about worker discontent.

He was last seen on January 25 heading from his apartment to meet a friend in central Cairo. He was on his way to the underground rail network, which was packed with security personnel scanning bags and checking commuters' IDs.

His body was found nine days later in an empty site along a highway in the 6th of October suburb on Cairo's western outskirts.

Ahmed Nagi, a state prosecutor investigating the Regeni case, said earlier that Mr Regeni's body carried marks of torture.

"All of his body, including his face" had bruises, cuts from stabbings and burns from cigarettes, Mr Nagi said, adding Mr Regeni appeared to have suffered a "slow death".

Egyptian media accused "evil hands" of orchestrating Mr Regeni's killing to damage Egyptian-Italian relations. The term is usually used to refer to Islamists, who have been targeted by a ferocious crackdown since the 2013 military ousting of Islamist president Mohammed Morsi.

The Italian media pointed fingers at the Egyptian security forces.

For years, rights groups have accused police of regularly torturing detainees. Over the past year, they have also accused them of using "forced disappearances" - detaining suspected activists or Islamists in secret without reporting their arrest.