The bomb attack was "unacceptable," Morsi's family said in a statement posted on the social networking website Facebook late on Sunday.

An explosive charge planted on top of a tree near the headquarters of the Foreign Ministry in downtown Cairo was detonated Sunday just meters away from a police checkpoint, leaving two policemen dead and five people injured.

A judicial source told Anadolu Agency earlier that one of the slain policemen, identified as Mahmoud Abu Serie, was a witness in the jailbreak case in which Morsi is a defendant along with 130 other people.

Assistant Interior Minister Abdel-Fattah Osman said in statements to the press that Abu Serie served in Boulak Abul-Ela, the commercial district where the blast took place.

Morsi's son, Osama, meanwhile, denied statement by two media anchors who said that his younger brother, Omar, welcomed Abu Serie's death on Twitter.

"These reports are unacceptable," Osama said. "Omar does not have a Twitter account," he added.

Morsi, among other charges, is accused of breaking jail along with 130 other people during the 2011 popular uprising that led to the downfall of Hosni Mubarak's autocracy of three decades.