CAIRO, Jan 30 (Aswat Masriya) - Egypt's President Abdel Fattah al-Sisi said on Friday that Egypt is "paying the price" for fighting terrorism and extremism, in reference to Thursday's deadly attacks in Sinai, state-run MENA reported.

Sisi described North Sinai's militant attacks as part of Egypt's "war against the strongest secret organisation in the past two centuries." 

At least 30 people were killed and 50 others were injured late Thursday in four separate attacks against security installations in the governorate.

Egypt's most active militant group Ansar Bayt al-Maqdis, which changed its name to Sinai Province since pledging allegiance to the leader of the Islamic State fighters in Iraq and Syria, claimed responsibility of the attacks on its Twitter account hours after they were launched.

"Egypt would have paid a much larger price ... had the [Muslim] Brotherhood remained in power," Sisi said.

Sisi cut short his visit to Ethiopia to attend the African Union summit on Friday following the attacks, the Egyptian presidency said in a statement.

The president declared a state of emergency and a curfew in the border governorate last October, in reaction to a militant attack which left over 30 security personnel killed.

It was extended until April 25, the cabinet said in a statement earlier this week.

Militants have stepped up attacks targeting security forces in Egypt, particularly in the Sinai peninsula, since the ouster of Islamist President Mohamed Mursi in July 2013.