At least 24 Egyptian policemen have been killed in an attack by suspected militants in the Sinai peninsula.

The attack on the police convoy, close to the town of Rafah on the Gaza border, was one of the deadliest on security forces in several years.

A state of emergency is in force across Egypt amid wider political turmoil following a military crackdown on Islamists in which hundreds have died.

Thirty-six protesters died in a prison van in the capital Cairo on Sunday.