ARISH, Egypt, July 20 (Xinhua) -- Unknown militants blew up a natural gas pipeline south of Egypt's Arish city of North Sinai governorate late Saturday, a security source told Xinhua.
"The targeted pipeline provides natural gas to plants in Sinai including a large cement factory and some military factories," the source added, noting that the assailants are believed to be extremist supporters of ousted Islamist president Mohamed Morsi.
The blast came a few hours after gunmen attacked a checkpoint in Egypt's western desert, leaving 21 soldiers dead and four others injured. A number of the attackers were killed in the explosion of an ammunition warehouse that resulted from fire exchange, according to the military spokesman.
Since Morsi's removal by the military in July 2013, gas pipelines in Sinai have been bombed several times. Al-Qaida-inspired, Sinai-based Ansar Bayt al-Maqdis group, which launched a number of anti-government attacks in Sinai, Cairo and some other provinces across the country, claimed responsibility for some of them.
Around 500 security personnel have been killed and hundreds of others injured in similar terrorist operations.
Islamist supporters of the deposed president, who condemned his removal as "a military coup," have suffered a massive crackdown with more than 1,000 of them killed and thousands others arrested.