The arrest of Radovan Karadzic has boosted Serbia's hopes of becoming a member of the "European family", Foreign Secretary David Miliband said today.
And Downing Street said today that compliance with the International Criminal Court on the former Yugoslavia was a condition of Serbia's admission to the European Union.
"The capture of Karadzic is an important step forward in that regard," the Prime Minister's spokesman said.
News of the capture of the notorious Bosnian Serb wartime leader coincided with a routine meeting of EU foreign ministers - with EU-Serb relations high on the agenda.
Negotiations on a so-called Stability and Association Agreement (SAA) - usually the prelude to full-blown EU accession talks - were suspended in 2006 as relations between Brussels and the Serb regime deteriorated.
Not least of the problems was the failure of the regime to fulfil a key EU condition for pursuing membership talks - hunt down and bring to justice Karadzic and his military leader Ratko Mladic, both indicted twice for war crimes by the War Crimes Tribunal in the Hague.
With one now in detention and being processed for despatch to the Hague to face trial, Mr Miliband made clear the issue of membership was back on the agenda - but not today.
Arriving in Brussels for the meeting, Mr Miliband said the fact that one of the most wanted men was now in detention was crucial, but today would not be the day for deciding on reopening the SAA.
"Justice for the victims of the terrible atrocities of the '90s require co-operation between the Serbian government and the International Criminal Tribunal on the former Yugoslavia.
"I look forward to that co-operation - we have always said that stability in the Balkans depends on justice for the relatives of those who suffered."
He said the foreign ministers would consider the reopening of the EU agreement with Serbia, but added: "Today is the day to congratulate the Serbian government, a day to say 'Well done' and to look forward to the next steps of co-operation with the Tribunal in the Hague."
Mr Miliband added: "We have always said that Serbia has a place in the European family and that place depends not just on cultural, economic and political issues but also on the European values of justice and human rights.
"The determination of the Serb government to do what the international community asked bodes very well for long-term relations."
The Dutch have been most opposed to resuming formal EU-Serbia talks, even after the election of a pro-EU, Western-looking government under Boris Tadic in May.
And today, a welcome for the arrest of Karadzic, one of the world's most wanted men, was mixed with quiet pressure now to catch Mladic.
Mr Miliband emphasised that now was not the time to set any new conditions on Serbia, but Mladic's name was always linked to that of Karadzic as a pair who had to be brought to justice before EU membership negotiations could get serious.
Karadzic, 63, on the run for more than a decade, is accused of being responsible for more than 20,000 deaths including Europe's worst atrocity for 60 years, the slaughter of 8,000 Muslims in the Bosnian town of Srebrenica.
"This arrest will help close the region's decades of conflict, and pave the way for a brighter, European future for Serbia and the region." said Mr Miliband.
The arrest was described by former EU High Representative for Bosnia and Herzegovina Paddy Ashdown as an "extremely important piece of justice for the world at large".
Lord Ashdown, who said he spent a great deal of time chasing Karadzic, said he was involved in the most "terrible and black period of crime" since the Second World War.
He said: "Karadzic was accused of being the architect of the worst war crimes that have been perpetrated in Europe since the Nazis.
"It will mean a major breakthrough for the Balkans region. It is a major credit to Serbia and at last brings the prospect of justice for Bosnia."
Karadzic was said to have been arrested "in an action by the Serbian security services".
He is accused of genocide, murder, inhumane acts, and other crimes committed during the 1992-1995 war.
His indictment alleges that he, acting together with others, committed the crimes to secure control of areas of Bosnia which had been proclaimed part of the "Serbian Republic" and significantly reducing its non-Serb population.
Karadzic is twice indicted for genocide over the 43-month siege of Sarajevo which claimed 12,000 lives and for orchestrating the 1995 massacre of some 8,000 Muslims at Srebrenica.
He had been hiding since 1998. In Sarajevo, streets were jammed last night with honking cars and euphoric crowds as Bosnian Muslims celebrated Karadzic's arrest.
Shadow foreign secretary William Hague commented: ""It is important that the world shows that no war criminal will ever be safe or indefinitely be able to escape."
"Bosnia needs justice and closure and this is an important milestone in this journey. We hope that Ratko Mladic will now also be swiftly apprehended."
A statement from the EU presidency, currently held by France, said the arrest was "an important step on the path to the rapprochement of Serbia with the European Union."
"This news gives us immense satisfaction. The new government in Belgrade stands for a new Serbia, for a new quality of relations with the EU," EU foreign affairs chief Javier Solana said in a statement.
"Radovan Karadzic will be facing a tribunal, having a fair trial, responding for many crimes. This is a good day for justice in the Balkans."Reuse content