KHARTOUM - Two Darfur aid workers held captive on a harsh mountaintop on the remote Sudan-Chad border for 107 days said they felt anger at mock assassinations by their captors but clung to the hope they would be released.

Nomadic tribesmen stormed the compound of the Irish aid agency Goal in Kutum, North Darfur, in July, held guns to the heads of Irishwoman Sharon Commins and Ugandan Hilda Kawuki and drove them off into the night.

We were just shocked, Commins said in an interview. I'd never seen that level of anger and sheer evilness in people's eyes.

To have people screaming at you in Arabic and pointing a gun to your head and then shooting bullets around you -- that's completely unacceptable.

The two women will return home Monday, thin, sunburned and still slightly dazed by their ordeal. They were held in the open on a mountaintop in such a harsh desert environment they said even their captors could not cope.

Any guard who had to guard us more than 10 days was literally cracking up, said Commins. There was very close to emotional breakdowns taking place and these were people who live there.

Kawuki said the armed men said no problem, this is just business, money in Arabic as they drove them for two to three hours through the desert landscape.

Commins said their young captors at times sympathized with them and some seemed to question the abduction.

There was moments when accidentally you'd start crying and you would see them ... and they would totally soften and ... they were on the verge of crying themselves.

There was genuine sympathy with us but they didn't equate that what they were doing was ruining us.

She said she almost lost hope when drinking water became scarce and time dragged on. Previous kidnappings in Darfur have rarely lasted more than two weeks.

Kawuki said she was determined they would get out even if they remained captive for years.

Even if I had to crawl out of here, see my family for five minutes and then drop dead, that's fine. I'd be happy with that, she said. (I had) no doubt I was going to get out.

Sudan's government said no ransom was paid for their release and vowed to bring the kidnappers to justice.

They have no way to escape punishment by all means -- If it is not today it will be tomorrow, Abdel Baqi al-Jailani, state minister for humanitarian affairs, told reporters.

A counter-insurgency campaign against rebels who took up arms in 2003 drove more than 2 million people from their homes and created a humanitarian crisis which the United Nations says has claimed 300 000 lives.

A series of kidnappings has taken place in Darfur in the past year and aid workers have stepped up security.

(editing by Andrew Dobbie)