Egypt has started work on a controversial buffer zone by destroying homes along its border with the Gaza Strip, following some of the worst attacks on the army since President Mohamed Morsi was ousted last year.

Bulldozers began destroying several abandoned houses along the frontier on Wednesday, just days after armed men attacked an army post killing 31 soldiers in the area.

Egypt has declared a state of emergency in the Sinai Peninsula and indefinitely closed the Rafah crossing, the only non-Israeli passage for Gazans. 

It also accelerated plans to create the 500-metre deep buffer zone, and told the area's 10,000 residents they had 48 hours to pack up and leave before they would destroy around 800 homes. 

The buffer zone will extend along the 10km border with Gaza, with water-filled trenches to thwart tunnel diggers.

Authorities say the border area is used by criminal gangs to smuggle arms from Gaza to Sinai, and have promised to compensate affected families with the monetary value of their properties and rent money for up to three months

Residents of Sinai, which has long been neglected by the state, say they rely on the tunnels for their livelihoods. But Egyptian security forces see them as a security threat and regularly destroy them.

Violence escalating

The Egyptian army has waged a broad offensive in northern Sinai against armed groups who have emboldened their presence in several areas in the neglected eastern region over the past three years, destroying much of the web-like network of smuggling tunnels that connect the area with Gaza.

Egyptian media has accused Gaza's Hamas rulers of meddling in Egypt's affairs, with some suggesting the group is supporting fighters inside Egypt since the military overthrew Morsi last year.

Hamas officials denied any interference and criticised Egypt for imposing stricter border crossing rules.

Since Morsi's toppling, attacks against security forces in northern Sinai have escalated, something Egyptian authorities blame on Morsi and his allies.

Morsi's Muslim Brotherhood group, which has been branded a terrorist organisation, denied links to violence.

Another al-Qaeda-inspired group, Ansar Beit al-Maqdis, has claimed responsibility for a number of attacks. No one claimed responsibility for Friday's attack on the army post.

Source: Al Jazeera and agencies