Hamas accused Egypt on Tuesday of torturing the sibling of a prominent member of the Gaza-based organization to death. Youssef Abu Zuhri, 38, the brother and former bodyguard of Hamas spokesman Sami Abu Zuhri, died Monday after being imprisoned in Egypt on April 28. Egypt has been mediating reconciliation talks between Hamas and Fatah for the past several months. Almost six months ago, Youssef Abu Zuhri was arrested in El-Arish after illegally crossing over the border via an underground smuggling tunnel from the Gaza Strip. During a Hamas press conference in Gaza on Tuesday, Sami Abu Zuhri said his brother had been brutally tortured over the past two weeks, leading to internal bleeding and ultimately a massive hemorrhage that caused his death. "My youngest brother died because of the barbaric torture he suffered in the Egyptian jail," Abu Zuhri said in an e- mailed statement. Egyptian Interior Ministry spokesman General Hamdi Abdel Karim denied that torture had been the cause of death; rather, Abu Zuhri "died a natural death from a drop in blood circulation," according to a report from Agence France-Presse. Other unnamed Egyptian security officials quoted by Reuters refuted Hamas's claims of torture, claiming that Abu Zuhri had suffered from liver and chest ailments and been transferred to Egypt's Alexandria Hospital for treatment in late September. The Cairo-based Egyptian Organization for Human Rights recently accused Egypt of torturing 13 prisoners to death between June 2008 and February 2009. Egypt has claimed that these were isolated incidents and not indicative of prison conditions. News agencies contributed to this report.