Foreign Secretary Jack Straw has spoken of the "malign influence" which former Yugoslav president Slobodan Milosevic had on the Serbian people.
Mr Milosevic was in office for 13 years until 2000.
Mr Milosevic, 64, was found dead in his cell on Saturday at The Hague, where he was standing trial for war crimes.
Lord Ashdown, former international envoy to Bosnia, said he regretted Mr Milosevic would not now face justice.
Former Tory foreign secretary Malcolm Rifkind said Mr Milosevic could appear pleasant but was also a vicious leader.
'Draw a line'
Mr Milosevic was facing charges of war crimes and crimes against humanity for his alleged central role in the wars in Bosnia, Croatia and Kosovo during the 1990s.
He also faced genocide charges over the 1992-95 Bosnia war, in which 200,000 people died.
Mr Straw said as he attended a meeting of EU foreign ministers in Austria that Mr Milosevic's death was "sad for his family".
But he urged the people of Serbia to look to the future.
"II hope his passing will enable the people of Serbia better to come to terms with their past, which is the only way in which they can properly face the future.
"What is important is that the region, in particular the people of Serbia, draw a line across Mr Milosevic's past and his life, which was a malign influence on the people of Serbia and the whole of the region."
Lord Ashdown - the former Liberal Democrat leader Paddy Ashdown - said many would regret that the justice progress had been halted.
"There is no doubt that of the evil that stalked the Balkans for the best part of a decade one way or another, one of the primary authors was Slobodan Milosevic."
'Act of closure'
He told BBC News 24 Mr Milosevic's death was "an act of closure".
"But it is not an act of closure that anyone would wish to see. The act of closure we wished to see was the end of the Milosevic trial and justice taking its course."
His views were echoed by Lord Owen, former British Foreign Secretary and the EU's special negotiator in Yugoslavia between 1992 and 1995.
He said the victims of his crimes had been deprived of the "crucial element - the verdict".
Lord Owen said: "My heart goes out to the victims.
"It was a fair trial, of that I have no doubt. I have no doubt, on most of the charges, Slobodan Milosevic would have been found guilty."
The former British Army commander in Bosnia, Colonel Bob Stewart, said: "I'm sad if Milosevic has died in custody because I very much wanted his trial to be brought to conclusion."
Former MP Martin Bell, who served as a BBC war correspondent in the Balkans conflict in the early 1990s, said: "History will not be kind to him and I think history will be right."
He said, however, that some would see the former president as a "tragic figure", and he added: "He was one of the aggressors, but not the only one."
Mr Bell described Mr Milosevic as a great orator who "knew which nerve endings to touch".
But he added: "The effect of what he did was to let loose the dogs of war."
Former Conservative foreign secretary Malcolm Rifkind said Mr Milosevic had been a complicated personality.
"I met him on one occasion in Belgrade during the Bosnian conflict - he was a very strange mixture of qualities because if you didn't know the background you could be quite easily persuaded this was a reasonable, very pleasant, very thoughtful man.
"But of course he was also very vicious leader - a man responsible for serious crimes and that is the way history will judge him."
Among the Serbian community in the UK there has so far been a restrained reaction.
A spokesman at the Serbian Orthodox Church in London told the BBC News website: "We have heard about it, but we have not made a decision on saying anything, we will be meeting to make a decision.
"People will pray for his soul - everyone in the church can pray."