An explosion in the Egyptian city of Alexandria has killed at least two people, including a policeman, in what officials called an assassination attempt against the coastal city's security chief.

The blast occurred near the Tolip Hotel on Saturday afternoon in Rushdi, a neighbourhood in Egypt's second city, close to the motorcade of Major General Mostafa al-Nemr, the head of security in Alexandria, an Egyptian security source told Al Jazeera.

The suspected car bomb, which also wounded at least four people, targeted the motorcade, the source said.

State news agency MENA quoted al-Nemr as saying that two people, a policeman and a driver, were killed in the blast.

The Egyptian Ministry of Interior said the attack was an assassination attempt against al-Nemr.

Former Deputy Interior Minister Rafiq Habib told Al Jazeera he suspects the perpetrators belong to an "extremist group", although nothing has yet been confirmed.

"The timing of this explosion, which comes just before the presidential elections, is telling of its objective to sow fear among voters," Habib said.

"I do not believe that it [the attack] will have any impact on the elections, however. I'm sure there will be huge numbers going to vote," he added.

Alexandria residents posted photos of smoke rising from the explosion site.

Sinai visit

The incident follows Egyptian President Abdel Fattah el-Sisi's visit to Sinai on Friday, before an election that is set to grant him a second term.

During the visit to a military and police station in Sinai, Sisi instructed the army to use all necessary force to root out armed groups in Egypt.

"We will come here soon to celebrate the victory over the Kharijites ("secessionists" from Islam) of this era," he said, referring to armed groups in the area.

A major operation was launched on February 18 with Egyptian ground, air and naval forces, along with border guards and police.

The army ordered hospitals to be placed on high alert, preparing extra beds and personnel, to deal with emergencies and medical evacuations.

Security operations against rebel groups in Sinai have been ongoing since 2000, but the uprising picked up after the military coup in 2013.

In late 2014, Egypt declared a state of emergency in the region, while Sinai's most active armed group pledged its allegiance to the Islamic State of Iraq and the Levant (ISIL, also known as ISIS).