By Shadia Nasralla and Stephen Kalin

CAIRO, June 25 (Reuters) - Eight people were hurt in northern Cairo when homemade explosive devices blew up at four metro stations and a courthouse on Wednesday morning in the first attacks in Cairo since Abdel Fattah al-Sisi became president earlier this month.

Three people were slightly wounded when a device - described by officials as "primitive" - exploded at Shubra El-Kheyma station in a northern district of Greater Cairo during morning rush hour, security sources said.

There was no immediate claim of responsibility. Egypt has been hit by a wave of violence, mainly by militants based in the Sinai peninsula against security forces, since the army ousted President Mohamed Mursi of the Muslim Brotherhood in July.

Shubra El-Kheyma appeared to be operating normally shortly after the blast, with passengers filing onto trains and a blackened, tattered cloth believed to have contained the device the only visible sign of the incident. Police with dogs were inspecting the site.

A spokesman for the Metro company - who said only two people were wounded at Shubra - said the system was functioning normally.

"I don't believe it's a big explosion ... The area itself was unaffected," Mohamed Abdel Zaher, the governor of Qalyubia province which forms part of Greater Cairo, told reporters.

Blasts were also reported at Ghamra, Hadaiq El Quba and Ezbet El-Nakhl stations, security sources said. Four people were hurt, they said, but their injuries were not life-threatening.

One person was hurt when a bomb attached to a car exploded near a Cairo court house, the sources said. Devices near the court house and at Hilmiyat El-Zeytoun station failed to explode, they said.

Security forces have been staging a crackdown on Islamists since Mursi's fall, killing hundreds and arresting thousands. Hundreds of policemen and soldiers have been killed by militants and in clashes since last summer.

"This is going to continue to be an issue so long as Islamists assess that they have no political space in which they can act and so long as the heavy handedness of the security forces continues," said Firas Abi Ali, Middle East and North Africa analyst at IHS country risk in London.

An Interior Ministry spokesman was quoted by the state news agency as blaming the Brotherhood for the attacks, calling them "desperate attempts ... to prove their presence in the street, especially in light of the current popular cohesion and state of stability which the country is witnessing."

The Brotherhood, which has repeatedly said it rejects violence, could not be immediately reached for comment.

Former army chief Sisi was sworn in as president after winning elections last month. His supporters believe he can save Egypt from chaos after more than three years of political and economic turmoil following the 2011 revolt that swept veteran autocrat Hosni Mubarak from power.

Egypt's judiciary has handed out mass death sentences to Islamists in recent months and on Monday jailed journalists from Al Jazeera television, accusing them of aiding the outlawed Muslim Brotherhood, drawing international condemnation. (Additional reporting by Ali Abdelaty and Reuters TV; Editing by Janet Lawrence and Sonya Hepinstall)