THE Bosnian government said yesterday that separatist Serbs still hold four of its citizens, a day after they freed 16 abducted civilians, apparently ending a crisis for Nato peace forces.
The Muslim led government said they were captured while travelling through the Serb held suburb of Ilidza on a road that Nato said was safe to use.
Earlier in the day Nato said a crisis caused by the abduction of the 16 was over and there was no proof that any other Muslims had been detained.
In Mostar an international administrator issued a sombre warning yesterday that rising tensions endanger the town after gunfire from a Croat sector badly wounded two Muslim policemen.
Their patrol car was struck by gunfire on Thursday evening in the southern town where uneasy Muslim Croat relations deteriorated since Croat police killed a Muslim youth on New Year's Day. One of the police officers was hit in the stomach, the other in the leg.
I hope serious people will understand how dangerous the situation is," European Union (EU) administrator Mr Hans Koschnick told reporters.
The tensions in Mostar are severely testing the Muslim Croat federation set up in half of Bosnia under the peace agreement overseen by troops of the Nato Implementation Force (Ifor).
EU officials also expressed concern over another flashpoint in Mostar, a hydroelectric dam above the town which almost burst before the new year. The Bosnian Croats were carrying out repairs on the dam without Muslim approval and EU mediated talks had bogged down in mutual recriminations.
The Croatian President Dr Franjo Tudjman, and the Bosnian President, Mr Alija Izetbegovic, met in Sarajevo on Thursday to discuss the problems besetting - the federation whose success is vital to the future of peace in Bosnia.
Ifor broadened its scope yesterday when Russia's parliament agreed to send 1,600 troops to Bosnia in Moscow's first joint military operation with its former Cold War Nato foe.
The Russian brigaders expected to arrive in February to serve alongside US troops in northern Bosnia.
Meanwhile, Nato said it had fired its first shots in anger since deploying in December when allied troops riposted on Thursday against a gunman who wounded an Italian sentry in the Serb suburb of Vogusca in Sarajevo.
Col Mark Rayner said five or six rifle rounds were fired at the assailant but it was not known whether he was hit.
Sarajevo has emerged with Mostar as the main testing ground for Nato peacekeeping after shots were also fired at a British transport aircraft this week and Serbs abducted 16 Bosnian civilians.
As part of efforts to build confidence, the Muslim Croat federation and Bosnian Serbs agreed in Vienna to exchange military liaison missions at each other's headquarters next month.
The deal was made within the Organisation for Security and Cooperation in Europe (OSCE) which is also trying to negotiate arms controls in Bosnia to reduce the risk of renewed fighting.