zurich switzerland sunday call quick release swiss woman report abduct sudan trouble darfur region rebel fight government decade foreign ministry aware case swiss woman kidnap darfur ministry spokesman say email local representation contact sudanese authorities efforts clarify situation progress switzerland call rapid unconditional release abduct person ministry give detail woman abduct detail swiss newspapers report woman aid worker sudan extend unilateral ceasefire rebel end december state news agency suna report sunday days unite state lift 20-year-old sanction tie progress resolve ongoing conflict conflict darfur begin 2003 mainly non-arab tribes take arm sudan arab-led government switzerland demand release swiss woman abduct sudan