SHEIKH ZUWAID, Egypt - Egyptian army and police forces stepped up roadblocks in north Sinai in a hunt for militant Islamists who kidnapped seven security officers last week, a security source said on Tuesday.The militants seized the men on a road between the towns of el-Arish and Rafah near the border with Gaza on Thursday in the latest setback for the Cairo government's efforts to reinstate law and order in the Sinai Peninsula. The desert region along Egypt's border with Israel has slipped into anarchy since autocratic president Hosni Mubarak was toppled by a popular uprising in 2011.His elected successor, Mohammed Morsi, ordered security forces almost a year ago to bring Sinai militants to heel after a deadly assault on a border post by Islamist gunmen.But the militants have proved resilient and the new hostage crisis has added to a pile of challenges confronting his government, including a financial crisis and street unrest.The security source said army and police forces had set up new roadblocks and reinforced existing ones in a zone running from the north Sinai town of c towards al-Jura further south. The goal was to choke off supplies and reinforcements for the kidnappers, the source said.Witnesses saw a military aircraft flying over a convoy of armored personnel carriers in the region.The state-run Al-Ahram newspaper said the security forces were seeking to surround the kidnappers but indicated they would first try to free the hostages without violence.One militant was killed late on Tuesday, in the first death since the operation began, when a mine that he was trying to plant in an area south of Rafah exploded, security sources said.Interior Minister Mohamed Ibrahim, in remarks published on state media on Tuesday, said the Sinai militants belonged to various jihadist groups including one based on Mount al-Halal that aimed to re-establish a mediaeval Islamic caliphate.He said that group had recruited members of the Palestinian Islamist Hamas movement that rules Gaza and had received training in using heavy weapons such as rocket launchers and anti-aircraft missiles. Those weapons were smuggled through tunnels from the Palestinian territory, Ibrahim said.The kidnappers had SAM-7 missiles as well as anti-tank weapons and rocket-propelled grenades, he added.The kidnappers are demanding the release of jailed Islamists. Morsi has ruled out talks with what he called "criminals" and vowed not to submit to blackmail.Cairo's 1979 peace treaty with Israel limits the number of troops it can deploy in Sinai, but Israel agreed to Egypt's request to send in more troops as security unraveled there in 2011. Israel has not commented on the new deployment.