ONE of Scotland's leading humanitarians who has been at the forefront of efforts to identify the victims of the Srebrenica massacre has called for intervention in Syria.

With the 20th anniversary looming of the atrocity which saw more than 8000 Bosnian Muslims massacred by Serb forces in the worst atrocity in Europe since the second world war, says governments can no longer fail to act when war crimes are committed.

Boys was part of the International Commission on Missing Persons (ICMP), which was set up in the wake of the conflict in the former Yugoslavia. The humanitarian organisation has been working to find the missing victims of Srebrenica, whose remains were often piled into different mass graves in a bid to conceal evidence of the war crime.

Boys says that initially the failure to stop the Srebrenica massacre led to a reaction where there was too much intervention in later conflicts - such as Iraq - "without proper planning". However, now governments are once again failing to act, he says in the wake of the Iraq War, when it comes to the on-going atrocities in Syria carried out by forces loyal to the government and by the terror group Islamic State, also known as Daesh by its enemies in the Middle East.

Two decades on from Srebrenica, Boys now believes one of the key lessons which have been learned from Srebrenica is that western governments can no longer treat those who go missing during war as an inevitable consequence of conflict and fail to search for them.

"We have calculated that something like 80,000 people have been disappeared in Syria - not simply killed in combat, but put into mass graves - there are very good aerial photographs of this." he said. "Yet we are not intervening, we are not doing anything.

"We said never again (after Srebrenica) and we said never again after the Holocaust, but when given the option of intervening, especially when it comes to Syria, we have just sort of said no, it is too difficult.

"Of course it is complex, but I think just saying it can't be done is not the right answer."

Today, some 6,390 of the 8,000 victims of the Srebrenica genocide have been identified. Out of more than 30,000 who went missing in Bosnia, just over 22,000 have been identified.

Boys, who was the chief operating officer of the ICMP for 14 years, will be among those attending a memorial service in Edinburgh on Friday July 10 to mark the 20th anniversary of the genocide. It is part of Srebrenica Memorial Week in the UK, organised by charity Remembering Srebrenica,which runs from Sunday 5 to Sunday 12 July.

Boys believes that, like the Holocaust, it is vital to continue to remember the massacre to help avoid it happening again.

"Unless we flag these things up, we will allow it to happen again, we will stumble into it," he said. "We could potentially have a situation where is happens again in Ukraine.

"Last year we (ICMP) sent a team there and already about 2,000 people have gone missing. You have got a vulnerable Tatar population in Crimea."

The ICMP has grown to become the world's leading organisation using DNA techniques and forensic science to identify those missing as a result of war, genocide, natural disasters and human rights abuses.

It has worked in countries including Iraq, Libya and Columbia, and following disasters such as the Asian tsunami in 2004 and the MH17 plane which crashed in Ukraine last year after being shot down.

Boys stepped down as chief operating officer last year to take up a new post as director of the International Institute for Democracy and Electoral Assistance, an organisation based in Stockholm which helps countries develop democratic systems.

He will receive an OBE next week, awarded in the 2015 New Year's Honours list for services to conflict prevention and resolution, particularly in the Western Balkans, and says he remains passionate about the issue of missing persons.

One case which Boys particularly remembers during the 20 years he spent in Bosnia - where he started as an aid worker - was a woman who started to doubt her own memory of her son as Serbian officials tried to deny the Srebrenica massacre had happened.

"All the people that lost relatives are also refugees - they had to flee from where they were and often had no belongings, no photographs," he said. "One lady was listening to the new reports saying this didn't happen, it is complete nonsense, the people didn't go missing and they are still living somewhere.

"Until we identified him, the only evidence she had of her son was a jar of Nivea moisturiser which she kept in the fridge, which had the imprint of his finger in the top of the cream.

"She felt she was almost going mad as there was this notion he didn't exist, that he hadn't left a trace."

Boys added: "There was an attempt to delete people from the historical record. A lot of what ICMP has done is to say they did exist - it is that simple."