CAIRO (AFP) - Suspected militants set off three small bombs on Sunday outside the home of an Egyptian judge who sentenced Islamists to death, wounding four people and damaging the building, police said.

Judge Mutaz Khafagi, who had also sentenced Muslim Brotherhood leader Mohamed Badie to life in prison, was in his first-floor apartment in the suburban Cairo building but was not injured in the explosions, a police official said.

Khafagi had sentenced 12 men to death in August 2014 after convicting them of murdering a police general in the town of Kerdasa, near Cairo, during a police crackdown targeting supporters of Mohamed Morsi, the Islamist president ousted in 2013.

Militants have carried out dozens of bombings across the country, often using small rudimentary devices, since Morsi's overthrow by the army.

Building security caught one of the "terrorists" who planted the bombs on Sunday after they emerged from a taxi, the police official said.

The other suspect escaped and remotely detonated the bombs after a crowd of onlookers gathered outside the house, the official said.

"The explosions damaged the facade of the judge's home... and broke the windows of three cars parked outside, including the judge's car," the officer said.

One of the four wounded civilians was taken to hospital with a neck injury and the others sustained minor wounds, a health ministry official said.

Jihadists say their attacks are in retaliation for a government crackdown targeting Morsi supporters that has left hundreds dead and thousands jailed.

The government unleashed the crackdown after army chief Abdel Fattah al-Sisi, who has since become President, overthrew Morsi following mass protests demanding the Islamist's resignation.