MINISTER for foreign affairs Micheál Martin will arrive in Khartoum this evening and begin crunch talks tomorrow with the Sudanese humanitarian affairs minister as efforts continue to secure the release of a kidnapped Irish aid worker and another woman intensify.

Nine weeks ago, up to eight armed men seized Sharon Commins (32), from Clontarf, Dublin, and Hilda Kawuki (42) from their compound in Kutum, a town in north Darfur. Both women work for Irish aid agency Goal.

Martin is due to meet the Sudanese humanitarian affairs minister Abdul Bagi al-Jailani, who has been overseeing negotiations to secure the women's release tomorrow. A government source played down the significance of the minister's decision to travel to Sudan, saying everyone remained optimistic about the women's imminent release.

Martin has been in regular contact with al-Jailani, and it was felt the "time was appropriate" for a face-to-face meeting between the pair.

The minister had been urged by some to visit the region sooner, but it is understood that timing was considered an important factor in attempts to secure Commins' release. "If he went too soon and got nowhere, there could be a sense that he played his hand too soon," said another source.

Two teams of officials from the Department of Foreign Affairs have been based in Khartoum and Darfur since the day after Commins and her colleague were kidnapped on 3 July. They have been liaising with the Sudanese government, which is in negotiations with tribal elders who are in touch with the kidnappers. The group is connected to a nomadic tribe in north Darfur.

The kidnapping has now become the longest-running abduction of foreign-aid staff in the region. Between March and July, two groups of humanitarian workers were captured. One group was held for three days, the other for more than three weeks, before being released unharmed.