A top Egyptian jihadist has been killed, security officials said Friday, just days before an election expected to sweep ex-army chief Abdel Fattah al-Sisi into the presidency on a pledge to eradicate terrorism. Shadi el-Menei, a senior commander of Egypt's deadliest militant group Ansar Beit al-Maqdis (Partisans of Jerusalem), was gunned down in an overnight ambush in his native Sinai Peninsula, the officials said. Word of his death, which was not immediately confirmed by jihadist sources, came on the last official day of campaigning for next week's election, in which Sisi is expectedly to comfortably defeat his sole rival, leftist Hamdeen Sabbahi. There were conflicting accounts of who carried out the ambush against Menei. Some officials said it was security forces, who intercepted him and other militants as they were preparing to bomb a gas pipeline. Others said that it was civilians from among the Sinai's heavily armed tribes. Ansar Beit al-Maqdis has claimed some of the deadliest and high-profile attacks on Egyptian security forces since the army overthrew Islamist president Mohamed Morsi last July. They have included a bombing at Cairo police headquarters last December and an assassination attempt against the interior minister in September, as well as frequent attacks on the security forces in the group's Sinai base. The US State Department designated the group a "foreign terrorist organisation" in April. Before Morsi's ouster, Ansar Beit al-Maqdis mainly targeted Israel, through attacks on the gas export pipeline through the Sinai to Israel and in January its fighters fired a rocket at Israel's Red Sea resort of Eilat. But since last July, the group has sharply escalated its operations, and the military-installed authorities say more than 500 people have died in the violence, most of them security personnel. The group is thought to have been founded in 2011 in the aftermath of the Arab Spring uprising that ended the 30-year rule of Hosni Mubarak. Its command structure and funding sources remain shadowy and analysts said that Menei was one of a number of leading figures within the group. One of the group's founders, Tawfiq Mohamed Fareej, was killed in March, when a car accident set off a bomb he was carrying. The army has poured troops into the Sinai in a bid to crush the militants, securing Israel's backing for the deployment in the sensitive peninsula where troop numbers are restricted under the two countries' 1979 peace treaty. The military-installed authorities have repeatedly blamed the surge in violence on Morsi's Muslim Brotherhood, which they designated a terrorist organisation in December, despite its repeated condemnation of the violence. "Vengeance is coming," Ansar Beit al-Maqdis warned Sisi earlier this year, and the group carried out twin suicide bombings outside the South Sinai provincial capital Al-Tur on May 2 on the eve of the launch of the election campaign. Sisi is running on a pledge to stamp out the violence and has promised that if he wins, there will be no place for Morsi's Brotherhood, whose top leaders are all in jail or exile. In his campaign appearances, he has played to the security credentials and strongman image that have endeared him to Egyptians weary of the turmoil that has ravaged the economy and its vital tourism sector since the Arab Spring. But his opponents say that if becomes president, Egypt will see a return to the autocratic rule of the Mubarak years. Voting takes place on Monday and Tuesday. Amnesty International said Thursday that dozens of civilians have been subjected to enforced disappearance and held for months in secret detention at an army camp north of Cairo. The detainees at the Al Galaa camp have been subjected to torture and other ill-treatment to make them confess to crimes, the watchdog said. "These are practices associated with the darkest hours of military and Mubarak's rule," said Amnesty's Hassiba Hadj-Sahraoui.