The southern leaders say the bombing runs may be a last-ditch attempt to ignite conflict and scuttle the agreement that calls for the Jan. 9 independence referendum. That vote will likely see Africa's largest country split in two.
Col. Philip Aguer, a southern military spokesman, said the north is making aggressive, calculated moves.
Northern officials deny the charges and say that southern military officials are hosting wanted Darfur rebels.
The referendum is part of a 2005 peace agreement that ended a 21-year civil war, which left nearly 2 million people dead.
Meanwhile, Zambia's government said Sudan's president, who is wanted internationally for war crimes, will skip a regional summit this week and send his foreign minister instead.
Zambia's state radio aired the information Tuesday. Zambia invited President Omar Bashir to the summit even though he faces a 2009 warrant. A Zambian government spokesman Monday said police would not have arrested him.
Opposition politicians in Zambia have criticized the decision to invite Bashir, who is wanted for crimes against humanity and genocide in suppressing the rebellion in Sudan's Darfur region. Several African nations and others have not carried out the International Criminal Court's warrant.
The summit, opening Wednesday, will review environmental issues.
