A bomb exploded in a car in Egypt's Alexandria near the convoy of the city's security chief on Saturday, killing a policeman, the government press office said. At least four others were wounded in the explosion.

The Egyptian Interior Ministry said the explosion occurred in the district of Roshdi as the head of the Alexandria Security Directorate was passing by.

No group has immediately claimed responsibility for the explosion.

The blast comes just days ahead of Egypt's presidential election, in which President Abdel-Fattah el-Sissi is virtually certain to be re-elected.

It also comes during a wide-scale security campaign targeting militants in the restive north Sinai Peninsula and other areas.

Egypt has been under a state of emergency since April 2017, when suicide bombings struck two Coptic Christian churches on Palm Sunday in an attack claimed by the local affiliate of the militant Islamic State group.