By Omar Fahmy
CAIRO (Reuters) - Four people, at least three of whom were policemen, were wounded on Monday when a bomb exploded under a traffic sentry post near a Cairo court, security sources said.
Bomb disposal experts defused a second device they found inside a black bag while searching the area following the blast, state news agency MENA said.
Egyptian authorities have pledged to end a wave of Islamist militant violence that has swept across the country but sporadic attacks on high-profile locations in Cairo and elsewhere have continued.
The explosion occurred in the affluent northeastern Heliopolis district and wounded four people, the health ministry said
It was claimed by Ajnad Misr, a militant group that emerged in January 2014 and has targeted security forces in and around Cairo.
"God Almighty made it possible for a company of our heroes to target a gathering of criminal security forces in the vicinity of Heliopolis Court with a bomb that led to the serious injury of two of their senior officers ... and a conscript," the group's media wing said on Twitter.
A two-year-old insurgency centered on the Sinai Peninsula has killed hundreds of soldiers and police since the army ousted President Mohamed Mursi after mass protests against his rule in 2013.
Sinai Province, which has pledged allegiance to the militant Islamic State movement that has taken over swathes of Iraq and Syria, is the most active group.
The violence is undermining efforts by the Egyptian government to revive investment and foreign tourism crucial to the economy and stability of the Arab world's most populous country.
While the insurgency is concentrated in the peninsula, which lies between Israel, Gaza and the Suez Canal, violence has also hit the capital.
Egypt's top public prosecutor was killed by a car bomb attack on his convoy in late June, the most senior state official to die at the hands of militants in two years.
Attacks have also targeted some of Egypt's tourism sites, including the Karnak temple in Luxor.
Separately on Monday a court referred 10 people to Grand Mufti Shawqi Allam, Egypt's most senior religious authority, a step required by law for convictions in capital cases, in a trial involving the brother of Al Qaeda leader Ayman al-Zawahiri.
Mohammad al-Zawahiri was not amongst those referred to the Mufti, meaning he escaped the death penalty in this case, judicial sources said. He and 67 others are accused of forming a terrorist organization with relations to Al Qaeda and targeting state institutions, the military, police, and Coptic Christians.
The court will issue a verdict on Sept. 27.
(Additional reporting by Ahmed Mohamed Hassan and Mohamed Abdellah, Writing by Ahmed Aboulenein, Editing by Yara Bayoumy and Angus MacSwan)