Egyptian security and military officials say Islamic militants have staged simultaneous attacks, including a suicide car bombing, on army checkpoints in northern Sinai, killing at least 30 soldiers.

The officials say Wednesday's attack took place just south of the town of Sheikh Zuweid and targeted at least six military checkpoints.

They say the militants also took soldiers captive and seized several armored vehicles. The officials spoke on condition of anonymity in line with regulations.

The attacks come just two days after the assassination in Cairo of the country's top prosecutor. President Abdel-Fattah el-Sissi vowed on Tuesday to step up a two-year crackdown on militants.

Militants in northern Sinai have battled security forces for years but stepped up their attacks following the July 2013 ouster of Islamist President Mohammed Morsi.