Jeremy McDermott in Colombia: A bodyguard was killed during the abduction

The assault on the church by left-wing rebels of the National Liberation Army (ELN) caught the security forces by surprise, but a pursuit by troops and helicopter gunships was swiftly organised.

The army is now trying to drop troops in ahead of the rebel column to cut them off, although it looks as if the rebels will be able to escape under cover of darkness.

Women cry at the church where hostages were taken

Most of the released hostages were women and children.

Witnesses said armed men entered the Roman Catholic church in the exclusive Ciudad Jardin district of Cali at about 11am (1600GMT) during Mass on Sunday.

The rebels forced the congregation, including women, chidren and a priest, outside and drove them away towards the poor district of Jamoundi, a known ELN stronghold.

Mayor Ricardo Cobo said around 150 people had been attending the service.

Jeremy McDermott: Soldiers from the third brigade are engaged in firefights

"It's very serious, the audacity of these groups," he added.

Police units and army patrols reportedly engaged in gun battles as they pursued the rebels.

Unconfirmed reports say two rebels and one bodyguard died during the incident.

President Pastrana has already done a deal with FARC

The ELN is believed to be Colombia's second-largest rebel organisation.

It is seeking to pressure the Colombian Government into granting a similar "safe haven" to the 42,000 square kilometre demilitarised territory enjoyed by the country's largest guerrilla group, the Revolutionary Armed Forces of Colombia (FARC).

On 12 April, five ELN rebels hijacked a domestic flight and ordered it to fly to a remote jungle airstrip. Twenty five of the 40 or more people on board have now been released.