It's a sad day today for the African Union - after last night's shoot-out in Khor Abeche. South Darfur, that killed three Nigerian soldiers and two Sudanese AU contractors (the AU's first casualties in Darfur), we hear of another incident this afternoon.

It appears that 18 troops (including an international observer) have been abducted near Tine, North Darfur. The latest news this evening indicates that two have been released (and are wandering through the desert as we speak trying to meet up with the AU vehicles out there looking for them).

While everyone has been noticing the increase in attacks against African Union convoys over recent months, it has not exactly been clear whether they were targeted at the troops or just part of the wider looting and raiding sprees that were affecting the NGOs. But incidents involving hour-long shoot-outs with casualties and the abduction of 18 (!) armed, uniformed men are pretty disturbing indeed.

As always, there is speculation. Are people angry at the AU for making such strong statements to condemn the government and the SLA rebels? Are the attacks really the work of rebels or is someone trying to make it look like this to undermine the peace process? Who is behind the planning and organisation - IS there planning and organisation? Who knows?

But, as usual in Darfur, I go to bed with more questions and worries than answers and ideas.

Tags: Sudan, Darfur, aid worker, African Union, attack, abduction