Fresh evidence of brutal treatment meted out by British forces to opponents of colonial rule in the 1950s has been revealed in secret files showing how they attacked and killed with impunity in Cyprus, where their victims included a blind man and a 17-year-old youth.

The incidents are among many disclosed in hitherto highly classified documents released at the National Archives in the wake of a court case relating to the other contemporary anti-colonial struggle – the violent repression of Mau Mau rebels in Kenya.

They describe how in July 1958, on a dark night but "with a bright moon", a patrol of soldiers from the Royal Ulster Rifles came across a group of Greek Cypriots, who started throwing stones. Two of them grabbed one of the soldier's guns and "hand-to-hand fighting took place", according to a report on the incident.

"A shot was fired … the fallen man was shot through the head." The Cypriots backed away but apparently ignored orders to stop. "This had no effect. One man, who was urging the others to attack the patrol and was obviously the ringleader, was selected and four shots were fired at him." The man was blind.

At the subsequent inquest, the coroner, James Trainor, said the corporal who killed "these two unfortunate people … had no other choice". He had showed "courage and very commendable restraint … At the least, he would have lost his company's arms and there was a grave possibility that they might have been all killed had he acted otherwise," the coroner stated.

He added: "There seems to be no doubt that one of the deceased was blind, but the fact that he got where he did get [moving across rugged countryside and over a ridge] suggests a fanaticism which would fully explain the description given to me of his standing in front of the crowd and waving it forward."

Andreas Louca, a 17-year-old Greek Cypriot, was fatally wounded when a soldier fractured his skull in clashes following the death of the wife of a British sergeant. Catherine Cutliffe was shot in the back in a Famagusta street in October 1958.

A young British army officer recorded seeing 150 soldiers indiscriminately "kicking Cypriots as they lay on the ground and beating them in the head, face, and body with rifle butts".

The officer described how he "forcibly restrained several such groups of soldiers who had completely lost their heads. Many of them were screaming abuse and the whole area resembled a hysterical mob … Several [Cypriots] appeared to be unconscious and bleeding profusely."

One report describes how a group of military police were seen "wantonly damaging windows and furniture" of the local "Communist Club". Even allowing for propaganda and exaggeration British troops behaved "brutally", a confidential official report noted. Trainor, who was also a judge, this time described the degree of force used by British soldiers as "entirely unjustified".

These incidents stand out from voluminous reports suggesting that most of the complaints made against British troops were indeed exaggerated and used as propaganda. However, the files show that the colonial authorities were seriously concerned about the number of genuine incidents of abuse by British forces.

London tried to brush them aside expressing the hope in a 1957 white paper on reports of brutality by British forces that it could "rely on the worldwide knowledge of their traditions of humanity and decency to convince the public of the free world of the falsity of allegations".

The documents released on Friday show how the colonial authorities covered up incidents by blocking visits to detention camps by MPs and journalists.

"I think that the best thing will be to refuse all permission for as long as we can," noted Hugh Foot, the governor of Cyprus (and father of the radical journalist and campaigner Paul Foot) in 1958.

The files show how the colonial administration in Cyprus played down the significance of a visit to the camps by the International Committee of the Red Cross and blocked independent inquiries.

A note from the governor's office in 1957 shows how British officials chose to regard the conflict in Cyprus. A senior official described it as "a hard and bitter struggle between the forces of law and order and an utterly ruthless terrorist movement and a political movement run by a church that is prepared to use any means to secure its political ends".

The terrorist movement was EOKA, led by Georgios Grivas whose aim was Enosis (Union with Greece. The church was the Cypriot Orthodox led by Archbishop Makarios. The files include a note by Foot about how Barbara Castle, a leading radical MP and future Labour cabinet minister, told him that Makarios had said at a meeting in Athens that he had decided to renounce Enosis but press for an independent Cyprus. The archbishop did so soon after in a move that finally led to the island's independence in 1960.

Many of the files, including those believed to refer to Cypriots who were informers for the colonial forces, have been withheld. Colonial files released at the National Archives also include papers relating to Basutoland (now Lesotho), the Cameroons, Ceylon (Sri Lanka), Fiji, the Gambia, Gilbert and Ellice Islands (Kiribati and Tuvalu) and Gold Coast (Ghana). Many files were destroyed by British officials shortly before these countries gained independence.