By Imogen Foulkes
BBC News, Bern
A Swiss court has begun hearing evidence in a landmark case between the Dutch government and the Swiss branch of aid agency Medecins Sans Frontieres.
Erkel was held for almost two years in Russia's Dagestan province
The Netherlands is suing MSF over ransom money it paid to release one of its workers held hostage for almost two years in Russia's Dagestan province.
The case is being watched carefully because of its implications for the future handling of kidnapping cases.
It marks the first time a national government has sued an aid agency.
Arjan Erkel is a Dutch citizen, but he worked for MSF Switzerland. He was taken hostage in Dagestan in August 2002.
His employers and his country tried to secure his release, although MSF claims the Netherlands did not move quickly enough.
He was not released until April 2004 - the longest period an aid worker has ever been held in captivity.
In the end, almost $1.25m (1m euros; £700,000) was paid for his freedom by the Dutch government.
It claims MSF asked for the money as a loan and promised to pay it back.
MSF denies this, saying its staff never even took part in the negotiations to secure Mr Erkel's release.
A Swiss judge will now have to decide the case after hearing evidence from the head of MSF Switzerland and from a Dutch foreign ministry diplomat.
At the heart of the dispute lies the reluctance of both parties to appear willing to pay ransoms.
Governments never admit to having done so.
Meanwhile, MSF has relief projects in trouble spots all over the world.
It fears donors will be less generous if they think their money is ending up in the hands of hostage-takers.