Researchers have discovered a Cold War “shoot-to-kill” order in what amounts to the clearest evidence yet that East German troops were given a licence to fire on people fleeing to the West, the Times of London reported.

The written order, issued to Stasi secret service agents, states: “Don’t hesitate to use your weapon even when border breaches happen with women and children, which traitors have often exploited in the past.”

It was found by a researcher in a regional archive of Stasi documents in the city of Magdeburg. The existence of a shoot-to-kill policy has long been assumed, given that more than 1,100 people were killed trying to flee East Germany. Most were shot trying to cross the Berlin Wall and the border between East and West Germany between 1961, when the frontier was sealed with the construction of the Wall, and November 1989, when it fell.

But senior Stasi agents and Politburo officials escaped prosecution or were given lenient sentences in a series of trials after German reunification partly because they maintained that no kill order existed, and no such written order was ever found.

Politicians and historians are suggesting that the document, dated October 1, 1973, could provide the basis for future prosecutions.

“This discovery is important because to this day officials kept denying that there was a firing order at the Berlin Wall, and we haven’t come across an instruction as explicit, clear and unlimited as this one,” said Marianne Birthler, head of the German Government’s Birthler Authority, which manages the Stasi files.

Written orders instructing border guards to open fire as a last resort have been found before in East German files but those orders always added that guards had to shout warnings or fire warning shots first.

There is no reference to such warnings in the seven-page order now uncovered. “This shows that the history of East Germany has yet to be fully researched,” said Andreas Schulze, spokesman for the Birthler Authority.

The find coincides with the 46th anniversary today of the building of the Berlin Wall. East Germany’s regime decided to seal the border to halt an exodus of people to the West. On the night of August 12, soldiers and workers tore up streets, put up barriers and barbed wire around the three Western sectors and began construction of the 103-mile wall that isolated West Berlin and turned it into a symbol of the Cold War for 28 years. Farther west, the 860-mile border between East and West Germany was fortified with fences, minefields and watchtowers.

The shoot-to-kill order was issued to a specially trained unit of Stasi agents ordered to infiltrate border guards and halt defections by regular soldiers. At least 37 border guards are known to have been shot dead while trying to flee across the frontier. “This document is a form of licence to kill. We haven’t seen anything like that before,” said Hubertus Knabe, director of the Stasi prison museum in the Berlin district of Hohenschönhausen. “It was only directed at Stasi agents but I think we have to establish whether this order was carried out, who gave it, what it led to. If we can establish that people were killed as a result of this order then of course state prosecutors will have to launch a criminal investigation.”

Ronald Pofalla, the general secretary of the Christian Democrats, led by Angela Merkel, the Chancellor, said: “The discovery of this firing order is frightening evidence of how inhuman this system was.”

Günter Nooke, a government human rights adviser, said that Germany needed to examine the history of East Germany more rigorously. “It’s astonishing that this document has only just been found.”