Twelve people were killed and around 100 were injured in an explosion at a security building in Egypt’s northern province of Dakahlyia on Tuesday, according to security and health ministry sources.

The sources said a car bomb exploded outside the police headquarters in Mansoura, Dakahlyia’s provincial capital, in the early hours of Tuesday.

The police chief of the province, General Sami al-Meihi, was injured in the blast, sources said.

According to Dakahlyia Governor Omar al-Shawadfi, parts of the building collapsed, leading to casualties among civilians in the street.

The blast comes a day after the Sinai-based militant group Ansar Beit al-Maqdis threatened the country’s soldiers with death unless they deserted the army.

The Sinai-based group has been blamed for an increase in attacks targeting security forces since the army ousted Islamist president Mohamed Morsy in July.

It claimed responsibility for September’s attempted assassination of Interior Minister Mohammed Ibrahim, as well as several car bombings and attacks on security headquarters.

Tuesday’s car bombing is the biggest attack so far outside the restive Sinai Peninsula and the Suez Canal area, indicating that militants are advancing towards the centre of the country.

It is the second attack in Mansoura since Morsy’s ouster.

In October, gunmen killed three policemen in an attack on a checkpoint in the city, 120 kilometres north of Cairo.

The government has been blaming Morsy’s loyalists and Islamist militants for the violence.

Morsy’s Muslim Brotherhood have condemned the attacks, but call on their supporters to protest across Egypt against the military-backed government.

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