The ELN is Colombia's second-largest leftist rebel group

The archbishop of Medellin, Luis Alberto Giraldo, said the left-wing rebels had refused to release all the hostages together.

Instead the National Liberation Army (ELN) wants to release the hostages one by one.

One hostage, Briton Matthew Scott, escaped by jumping down a ravine.

The archbishop said on Thursday night the other hostages were unlikely to be released soon.

"You can see that we are all left with long faces," he told reporters in Medellin.

HOSTAGES HELD Israelis: Beni Daniel, Ortaz Ohayon, Ido Joseph Guy, Erez Altawil Spaniard: Asier Huegun Briton: Mark Henderson German: Reinhilt Weigel

He had spent six hours negotiating with jailed ELN member Francisco Galan.

The ELN proposes releasing the hostages one by one, starting with the handover of a Spanish Basque citizen.

The Church now fears the conditions laid down by the ELN may scupper the chances of the first hostages being released next week, as promised earlier by the rebels.

The other foreigners still being held are four Israelis, a German and one Briton. The hostages were seized while hiking in the northern Sierra Nevada mountains on 12 September.