EGYPT’S military has detained four US nationals after they took photographs in a restricted zone by the Suez Canal, a military official says.

“Three US nationals and their translator, a US-Egyptian dual citizen, were detained in the Port Tawfiq harbour,” the official said, without identifying them.

“Residents of Suez had seen the four taking pictures and informed the military authorities. They are not reporters for any media and did not have permission to take photographs,” the official said.

Tensions have been high in Suez after a court last week confirmed the release on bail of police accused of killing protesters in the city during the uprising that ousted former president Hosni Mubarak earlier this year.

The army was forced to intervene on Sunday to clear several hundred protesters who were blocking a highway outside the city, while last Wednesday hundreds of people torched police cars and tried to storm government buildings in Suez.

The city is located near the southern terminus of the Suez Canal, a strategic hub of global maritime transport.

The seven police released on bail are among 14 facing trial over the killing of 17 protesters and wounding of 300 others.

The other seven are on the run and being tried in absentia.

The case comes amid heightened tensions in Egypt over the handling of legal proceedings against security forces who used deadly violence in the uprising, killing 846 civilians and wounding thousands, according to official figures.