A fire that killed 11 people at an orphanage in Algeria's capital was caused by an electrical spark from a faulty air-conditioning unit, police in the North African country have said.

Amid the summer heat, the air conditioner had been running continuously before the blaze broke out in the early hours of Thursday morning, according to forensic investigators.

The civil protection department has not specified the ages of those killed or the 19 injured, but in a social media post Algeria's President Abdelmajid Tebboune said children were among the dead.

The fire service battled the flames at the children's care home in Mohammadia, an eastern suburb of Algiers, for at least three hours.

A carer working at the orphanage was amongst those who died, according to the AFP news agency quoting a police report.

Prime Minister Sifi Ghrieb has visited survivors at two hospitals, where they are being treated for burns, smoke inhalation and shock.

Algeria is experiencing an intense summer heatwave, with firefighters also battling several wildfires across northern Algeria.

News of the orphanage fire has shocked and outraged many.

"May God have mercy on them," the civil defence unit said as it announced the death toll on Thursday, several hours after the blaze began.

President Tebboune said in a statement: "It is with a heart resigned to the will of God that I learned of the death of children and the injury of others."

The authorities said five children with reduced mobility had been safely rescued from the blaze.

The fire has prompted opposition figures, critical media and social media users to demand answers over possible negligence.

The opposition Jil Jadid party called for a transparent investigation into the incident and legal accountability for any negligence or safety failures.

It also demanded a nationwide review of fire safety standards at orphanages, care homes, hospitals and schools.

Journalist Akram Kharief described the fire as a "national tragedy", called for fire safety audits at all public institutions and questioned why Algerians could not live "a normal life in a normal country".

Comments on the social media pages of several news outlets asked who had been supervising the children overnight, while some called for resignations.

Meanwhile, Le Matin d'Algérie - a website critical of the government - noted the absence of the mayor and provincial governor during the initial rescue operation.

Pro-government news site Algerie Patriotique said the country should establish the truth "without complacency" and determine whether the deaths could have been prevented.