CAIRO (AFP) - Two bombs exploded on Saturday in a Cairo suburb killing a teenager and wounding a woman, officials said, the latest in a string of blasts to hit the Egyptian capital this week.

Militants have stepped up attacks in Egypt after the army ousted Islamist president Mohamed Mursi in July 2013 and a deadly crackdown by authorities on his supporters.

The makeshift bombs were planted in a telecommunications building still under construction in the October 6 suburb and set off by a mobile telephone at around 9am (0700 GMT), a police investigator at the blast site told AFP.

"An 18-year-old girl has been killed and a woman has been wounded," said senior health official Ahmed al-Ansari.

Residents said the blast was powerful and shook windows of nearby buildings.

Security officials said the teenager was the watchman's daughter.

Saturday's blast comes after five makeshift bombs exploded at four Cairo metro stations on Wednesday, while a sixth one blew up at a courthouse. Six people were wounded in those blasts.

The authorities have blamed Mursi's Muslim Brotherhood for attacks rocking the country, most of which have targeted security forces, and have blacklisted the Islamist movement as a terrorist organisation.

Since Mursi's ouster, a crackdown on his supporters has left more than 1,400 people dead and seen at least 15,000 jailed. Hundreds have also been sentenced to death.

An Al-Qaeda inspired jihadist group based in the Sinai Peninsula, Ansar Beit al-Maqdis (Partisans of Jerusalem), has claimed some of the deadliest attacks on security forces, as well as a failed assassination attempt against the interior minister in September.

A little-known jihadist group, Ajnad Misr (Soldiers of Egypt), has also claimed a string of attacks on police in Cairo.

The government says the militants have killed about 500 people, most of them security personnel.