Egyptian forces have taken over 37 schools and transformed them into military bases while dozens more have been destroyed during a 10-year war with militants in Sinai, a rights group has found in an initial assessment.

In a months-long investigation shared with the Guardian before its official release, the UK-based Sinai Foundation for Human Rights (SFHR) accused the Egyptian armed forces of compromising the right to education of children during its campaign against militants in north Sinai.

Using satellite images, video, photos and testimony from witnesses who live in the sparsely populated area, the group found the army had carried out the “unnecessary targeting of certain schools”, causing “community-wide shock”.

Ahmed Salem, SFHR’s co-founder and executive director, said: “Schools are used as bases because they are often built two or three storeys high, whereas most of the buildings in the area are one story. It gives the military a place to position snipers.”

SFHR said it found 59 schools had been destroyed in clashes between the army and insurgents, and added that in three cases, schools were attacked or destroyed by militants. Students have been left with “no education and heightened illiteracy”, SFHR said.

Since 2013, Egypt has battled an Islamic State-linked insurgency in Sinai, with militants carrying out scores of attacks on security forces and civilians. The conflict followed the 2011 Egyptian revolution, in which Hosni Mubarak was overthrown, only for the Islamist government that replaced him to be deposed in a military coup.

Gen Abdel Fatah al-Sisi, who orchestrated the power grab, continues to rule today and has in recent years intensified the large-scale offensive in the vast Sinai peninsula.

The toll of the conflict on civilians has been hard to determine as operations have largely been hidden from the public, with journalists and outside observers barred from the area. The violence has mostly avoided tourist resorts at the southern end of the peninsula.

Satellite images provided by SFHR showed schools with a military presence, including the construction of radio towers and fortifications, such as brick walls built in the surrounding area.

Images of al-Mahdeya joint elementary school in the Rafah region showed that farmland immediately surrounding the school had been razed, SFHR said. Videos taken at ground level showed military personnel and armoured vehicles inside the school.

The rights group cited a father whose children attended al-Mahdeya, who said two of his three children had since ended their education as schools in other areas were not equipped to provide extra places. The government had failed to adequately relocate children after taking over their schools, SFHR said.

Another school, al-Shatea joint elementary school in the Sheikh Zuweid region, was completely destroyed, according to a video showing the building in ruins.

Separate video by pro-government armed groups in Sinai showed broken desks and a blackboard damaged by shrapnel.

In other cases, militants had placed explosive devices inside schools to prevent the army from using them, SFHR said.

The Egyptian government and militants have been accused by rights groups of committing crimes during the hostilities in north Sinai, home to roughly half-a-million people. Human Rights Watch has previously alleged that warring sides have violated the laws of war as well as committed human rights abuses. It also claimed security forces killed dozens of alleged terrorists in “extrajudicial killings”.

A growing body of international law and UN security council resolutions have led to a consensus that schools should be protected from military use during armed conflict.

SFHR said it had sent letters to the Egyptian minister of education, chair of the education committee in the Egyptian parliament, governor of north Sinai and undersecretary of the Ministry of Education in north Sinai to comment on its initial findings but had not heard back.

The government has previously claimed in local media that it had funded the construction of new schools across north Sinai over the past few years. SFHR disputes this, saying 96 schools in north Sinai cannot be used and many children officially enrolled in school are, in fact, out of education.

The Guardian has contacted the Egyptian ministry of foreign affairs for comment.