Switzerland has signed a new treaty outlawing the death penalty under any circumstances, including during wartime.
The Council of Europe presented the 13th protocol of European Convention on Human Rights in Vilnius, Lithuania. It is the first international treaty to abolish capital punishment entirely.
The Swiss foreign ministry said the aim was "a Europe without capital punishment".
Peacetime executions are already outlawed by the Convention's sixth protocol, which went into effect in 1985. Forty European states have ratified it.
Only Russia, Armenia, Bosnia and Turkey have failed to complete the process, but all have applied a moratorium on executions since at least 1996.
The Council of Europe's Secretary General, Walter Schwimmer, said the occasion was another step towards the total abolition of the death penalty worldwide.
"The Council of Europe was already proud to have banished the death penalty in peacetime on a continent where more than 800 million people live. With Protocol 13, it opens the way to abolishing this barbaric punishment in all circumstances.
"We hope that this will be a decisive step towards a universal abolition of the death penalty and we shall spare no effort in achieving this."
Last execution in Switzerland
The death penalty was dropped from the Swiss penal code in 1937 - the last execution took place in 1940 - and from the military code in 1992. It was also specifically banned in the Swiss constitution in 1999.
Switzerland has long been a strong advocate for the abolition of capital punishment. The Swiss authorities called for an outright ban during the United Nations Human Rights Commission session last March.
The latest protocol is up for ratification by the Council of Europe's 44 member states. So far, only 30 have pledged to do so, including Switzerland, although only ten have to ratify the treaty for it to go into effect.
The abolition of the death penalty in peacetime has been a pre-requisite of entry into the Council of Europe since 1994. The last known execution in a member state took place in 1997 in Ukraine.
US and Japan remain unmoved
According to Amnesty International, 90 countries still apply capital punishment, including the United States and Japan. The two nations could see their observer status at the Council of Europe called into question if they refuse a moratorium on executions.
The Committee of Ministers of the Council in Vilnius will also discuss the fight against terrorism, human rights and regional cooperation. The Swiss delegation, led by the secretary of state Franz von Däniken, will reaffirm the necessity to respect human rights and international humanitarian law when fighting terror.
swissinfo with agencies