(SARAJEVO) - An EU peacekeeping helicopter crashed Thursday in a heavily forested, mountainous region of central Bosnia, killing all four people on board, officials said.

The EUFOR helicopter went down near the central town of Travnik, at around noon (1000 GMT), shortly after the crew made a Mayday call, the peacekeeping mission said.

Those killed were two Spanish crew members and German soldiers, Spain's defence ministry said in a statement.

"It is with our deepest sadness that there were no survivors," EUFOR commander Spanish Major General Ignacio Martin Villalain said in a separate statement.

The twin-engine MBB BO-105 helicopter belonging to the Spanish military had taken off on a routine flight around half an hour earlier from Camp Butmir in the Bosnian capital Sarajevo.

It had been "transporting personnel" when it went down some 20 kilometres (12 miles) north of Travnik "for reasons that are not yet known," said the ministry.

The Spanish general lamented the loss of life in his statement, and said that they were still investigating what had happened.

"Respect the loss today of our four comrades. Their lives were unfortunately cut short whilst actively engaged ... in support of maintaining a safe and secure environment" in Bosnia, said Villalain.

According to local police, the accident happened in an area where there are still some land mines remaining from Bosnia's inter-ethnic war of the early 1990s.

Meanwhile, the top international envoy to Bosnia, Miroslav Lajcak, expressed his condolences to the victims' families and friends.

"They were here to serve the citizens of Bosnia-Hercegovina and for this we owe them our deepest gratitude," Lajcak, also EU special representative to Bosnia, said in a statement.

The European Union's peacekeeping mission, EUFOR, took over from a NATO peacekeeping mission in 2004.

Charged with military tasks set out in the peace deal that ended the 1992-1995 war, it currently has around 2,200 troops in the former Yugoslav republic.

In January, 11 Macedonian soldiers serving with the EU peacekeeping mission were killed when their helicopter crashed near Macedonia's capital Skopje.

Spain has 258 military personnel in the EUFOR peacekeeping force in Bosnia -- 220 of them in Sarajevo and 38 in other regions.

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