A string of blasts has hit the Egyptian capital Cairo, killing one person and wounding three others, a health official and police said.

Health ministry spokesman Hossam Abdel Ghaffar said the bomb at a pizzeria tore off the legs of the victim who was pronounced dead in hospital. Two other people were wounded in Thursday's attack.

The bombs went off outside two offices of British firm Vodafone and a branch of United Arab Emirates-owned Etisalat, an interior ministry spokesman told the AFP news agency.

The branches were closed at the time of the explosions.

It was not immediately clear why the cell phone companies and restaurant were targeted, but Abdel Latif of the interior ministry said authorities had been on the alert for attacks in the runup to parliamentary elections next month.

Fighters have set off dozens of bombs in the capital since the army overthrew Mohamed Morsi in July 2013 and cracked down on his supporters, killing hundreds of protesters in street clashes.

Most of the bombs have been rudimentary and caused no casualties.

But several have killed policemen, including two senior officers killed while attempting to defuse bombs planted outside the presidential palace in June last year.

In the Sinai Peninsula where they are based, the fighters who have pledged allegiance to the Islamic State in Iraq and the Levant have killed scores of soldiers and policemen since Morsi's overthrow.

Source: AFP