Martti Ahtisaari, the former Finnish president awarded the Nobel peace prize for his mediation in Kosovo and a string of other conflicts around the world, said on Friday that Serbia would have no option but to accept the new Balkan state.

In his first interview with a British newspaper since being named Nobel laureate last week, Ahtisaari shrugged off the apparent setback to his work in Kosovo inflicted when Serbia succeeded in having its declaration of independence referred to the international court of justice.

The 71-year old also argued that it did not matter that the former Serbian province had been recognised so far by only 51 of the world’s 192 countries. That was less important than the economic clout of the nations that did recognise Kosovo, including the US and most of western Europe.

“It really doesn’t matter if Paraguay hasn’t recognised,” Ahtisaari said. “Well over 65 per cent of the wealth of the world has recognised. That matters.”

Ahtisaari was commissioned by the UN in 2005 to find a compromise solution for Kosovo’s status as a way of ending the deadlock that followed the 1999 war and Nato intervention. His plan for supervised independence coupled with extensive minority rights for Kosovo’s Serb minority was rejected by Serbia and Russia last year. However, Kosovo – with western backing – declared independence in February.

Belgrade has vowed never to accept Kosovo’s sovereignty, but Ahtisaari said Serbia would have to relent if it wanted eventual European membership. “You can’t be poking the EU in the eye [while] saying you want to join EU,” he said.

He sent private messages to all parties soon after taking his role as mediator, that Kosovo’s secession was inevitable. “[I said] in light of what had happened in Kosovo, the return of Kosovo to Serbia is not a viable option,” Ahtisaari said. “So since March 2006 no one should have had any illusion what my plan was going to be.”

Russia furiously opposed Kosovo’s independence, and pointed to it as justification of its own recognition of Abkhazia and South Ossetia, pro-Russian enclaves in Georgia. Ahtisaari rejected the parallel.

“We did Kosovo within the UN framework. In Georgia there was not even an attempt,” he argued. “You cannot go into an independent country and do whatever you like. Even if you are Russia.”

Ahtisaari was also involved in mediating Namibia’s independence from South Africa in 1989, and brokering peace in 2005 between the Indonesian government and separatists in Aceh. He said the secrets to successful peacemaking were research, having a clear strategy, and hiring staff who offer independent thinking. “You don’t need a single yes man,” he said. “You have to have colleagues who can challenge your own thinking.”—Dawn/Guardian News Service