A state of emergency is in force across much of Egypt’s Sinai Peninsula after 30 soldiers were killed in a suicide car bombing by suspected jihadists.

It was the deadliest attack on the country’s security forces since the army deposed Islamist president Mohamed Morsi last year, to the fury of his supporters.

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The state of emergency in the north and centre of the Sinai will remain in place for three months, the president’s office said.

A curfew is in force from 5 pm to 7 am.

Egypt also announced it would close the Rafah crossing into the Gaza Strip, the only route into the Palestinian territory not controlled by Israel.

“The army and the police will take all necessary measures to tackle the dangers of terrorism and its financing, to preserve the security of the region… and protect the lives of citizens,” the presidential decree said.

Egyptian President Abdel Fattah al-Sisi. Photo: AAP

President Abdel Fattah al-Sisi, the army chief who toppled Morsi and later won elections, chaired a meeting on Saturday of the Supreme Council of the Armed Forces to discuss what measures to implement under the state of emergency.

After the meeting, Sisi said Friday’s attack was carried out with “external support” in order to “break the will of the Egyptian people and army”.

Security officials said a suspected jihadist rammed a checkpoint with an explosives-packed vehicle.

The attack in an agricultural area of El-Arish, the main town in north Sinai, also wounded 29 troops, medics said, including a senior army official and five officers.

Gunmen also shot dead an officer and wounded two soldiers on Friday at another checkpoint south of El-Arish, security officials said.

Jihadists in the peninsula have killed scores of policemen and soldiers since Morsi’s overthrow to avenge a bloody police crackdown on his supporters.

The attacks have dealt a further blow to a tourism industry already reeling after a 2011 uprising that overthrew long-time president Hosni Mubarak.

While south Sinai is dotted with tourist resorts on the Red Sea – a popular destination for scuba divers – the lawless north is a base for militants who have launched a wave of attacks, mostly targeting security forces.

The peninsula’s southern coastline has been largely spared from the violence rocking the country since the 2011 revolt, partly thanks to security checkpoints in the region.

But it has not been completely untouched by the militants.

In February, a suicide bomber killed three South Korean tourists in an attack on a bus in the south Sinai resort of Taba that was claimed by Ansar Beit al-Maqdis, the most active militant group in Egypt.

After Friday’s attack, Sisi announced three days of national mourning.