Egypt began demolishing houses along its border with Gaza on Wednesday to set up a buffer zone to prevent militant infiltration and arms smuggling following a wave of deadly attacks.
The move, which will see about 800 homes razed, comes after a suicide bomber killed 30 soldiers in Egypt's Sinai Peninsula, which borders the Palestinian territory, last Friday.
It also comes two days after President Abdel Fattah al-Sisi enacted a decree allowing military trials for civilians suspected of attacking state infrastructure, as he promised a tough response to what he called the "existential threat" posed by the militants.
"The president is monitoring the area along the border ... especially the area that is being evacuated for eliminating terrorist hideouts and to prevent any infiltration of terrorists that will threaten national security," his office said.
The authorities want to establish a 500 metre (yard) wide buffer zone along the 10 kilometre (six mile) long border with Gaza.
Prime Minister Ibrahim Mahlab issued a decree on Wednesday formally ordering the establishment of the buffer zone.
"If any resident of the area earmarked to be closed off does not move out voluntarily, his property will be confiscated," said the decree, carried by state news agency MENA.
In the town of Rafah, which straddles the Egypt-Gaza border, witnesses reported seeing dozens of families leaving homes on the Egyptian side, their furniture piled into trucks.
Bulldozers began razing abandoned houses along the border as military helicopters hovered overhead.
The authorities said those whose homes were demolished would receive compensation, but not all residents were convinced.
"We are for national and border security, but not at the cost of our homes and interests," said Wissam al-Agha, a Rafah doctor, whose house lies within the area earmarked for the buffer zone.
- 'Shift in strategy' -
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North Sinai governor Abdel Fattah Harhur said emergency assistance would be provided to everyone affected, with families receiving 900 Egyptian pounds ($125, 100 euros) to cover rent for three months.
Analysts said the buffer zone marked a major shift in Egypt's strategy against the militants.
"It is an operation to isolate terrorists in an area empty of people, in turn facilitating targeting of terrorists and also reducing civilian casualties," said Eman Ragad, an expert on regional security at Al-Ahram Centre for Political and Strategic Studies.
Sisi already issued a decree on Monday placing state infrastructure, including power lines and major roads and bridges, under military protection for two years.
He gave military tribunals powers to try civilians accused of attacking such infrastructure.
Egypt suspects Palestinian militants of aiding jihadist attacks that have increased since the army ousted Islamist president Mohamed Morsi in July last year.
The army has stepped up its destruction of tunnels from Gaza that it says are used to smuggle arms, demolishing more than 1,600 since Morsi's ouster.
"Families whose houses have openings to these tunnels will not be compensated," governor Harhur told private television channel CBC Extra.
Following Friday's bombing, Egypt imposed a three-month state of emergency across much of North Sinai and closed the Rafah crossing -- the only entry point to Gaza not controlled by Israel.
No group has claimed responsibility for the attack.
Jihadist groups based in the Sinai have killed scores of policemen and soldiers since Morsi's overthrow.
They have said their campaign is in revenge for a police crackdown on the ousted president's supporters that has left more than 1,400 people dead.