Hamas has been accused of providing weapons, training and fighters for Sinai-based insurgent attacks, although Hamas strongly denies the allegations, calling them a smear campaign aiming to harm relations with Egypt. According to the Egyptian Army, since the ouster of Egypt's Muslim-Brotherhood president Mohamed Morsi, over 600 Hamas members have entered the Sinai Peninsula through smuggling tunnels. In addition, several weapons used in Sinai's insurgent attacks are being traced back to Hamas in the Gaza Strip, according to the army. The four leading insurgent groups in the Sinai have all reportedly maintained close ties with the Gaza Strip. Hamas is also accused of helping Morsi and other high-ranking Egyptian Muslim Brotherhood members break out of the Wadi Natroun prison in Cairo during the 2011 revolution. Hamas called the accusation a "dangerous development". Egyptian authorities stated that the 2011 Alexandria bombing was carried out by the Gaza-based Army of Islam, which has received sanctuary from Hamas and earlier collaborated in the capture of Gilad Shalit. Army of Islam members linked to the August 2012 Sinai attack have reportedly sought refuge in the Gaza Strip. Egypt stated that Hamas directly provided logistical support to the Muslim Brotherhood militants who carried out the December 2013 Mansoura bombing.