Arjan Erkel, a Dutch citizen employed by Medecins Sans Frontieres (MSF), was abducted by gunmen in the Dagestani capital, Makhachkala, on 12 August 2002.

The organisation says it has seen photographs which suggest he is still alive.

The Russian Government has also assured MSF that he is alive. However, the Russian inquiry has gone no further, MSF says.

There has been no ransom demand for Erkel

"It is a scandal that, after one year, our colleague Arjan Erkel is still missing," said Dr Morten Rostrup, International President of MSF.

"This can only be attributed to the mishandling of the investigation and a lack of commitment by Russian authorities."

The organisation criticises the Dutch Government and other Western states for "lack of energy" in pressing for action from Russia.

Leads

It points out that the Russian authorities have been able to provide some details of Mr Erkel's living conditions and to maintain contact with his captors.

We have to speculate ourselves as to the reason for the lack of will from the Russian authorities to resolve the case Thomas Nierle, MSF Switzerland

"Given these leads... MSF finds it increasingly difficult to understand why the hostage remains in captivity," says a letter to Russian ambassadors in every country where the organisation has an office.

The head of operations for MSF Switzerland, Thomas Nierle, was quoted on Tuesday in the French Liberation newspaper suggesting that Russia might not want Mr Erkel released.

"Is it that the continued kidnapping of Arjan dissuades humanitarian organisations from working and witnessing the truth in the North Caucasus and helps the Russians to pretend that there is normalisation in the region?" he asked.

He said that the official Russian line - that Mr Erkel was being held by gangsters - was questionable because no ransom request had been made.

Investigation halted

As former hostages we know the sight of basement walls and the terror of not knowing why or by whom you are held Kenny Gluck

MSF is also concerned about evidence that two officers of the Russian Federal Security Service were present when the abduction took place - but failed to intervene or give chase.

Mr Rostrup said the organisation was also "dismayed" to learn that the Russian investigation into the case was halted in November 2002, and only re-opened in May 2003.

"We were not told of this," he said. "Instead the authorities kept assuring us they were doing everything to secure Arjan's release."

Another MSF employee who was kidnapped in the Caucasus, Kenny Gluck, says out that 27 aid workers have been taken hostage in the region "over the last seven years of tragedy in the Caucasus".

"Our hearts go out to Arjan and his family. From our own experience we know the pain and trauma this must cause," he writes.

"As former hostages we know the sight of basement walls and the terror of not knowing why or by whom you are held."