When traveling from Khartoum to Juba, make sure that Sudan Air has not canceled its flights to that most southern part of the country. Sudan Air's erratic schedule to Juba may irritate the incidental foreign traveler. But to the south Sudanese - increasingly disaffected 11 years after a civil war - it is yet another sign of neglect and mistreatment of the south by the north.
The south's disillusionment with the negotiated end to Sudan's 17-year-old civil war has lead to rising lawlessness and a bitter dispute over the future of the area's autonomous government.
Many see the deteriorating security situation and the ever more frequent violence as a potential threat to plans to construct a $1 billion oil pipeline from the south to Port Sudan - which the government hopes will help overcome Sudan's staggering economic problems.
Observers in Khartoum cite reports of various groups in the south arming themselves.
''There is no doubt that arms in the south are easily available,'' one well-informed source said, adding that ''there is evidence that the violence amounts to more than simple tribal feuds.''
Southerners have a long list of grievances. Most complaints go back to the roots of Sudan's civil war: accusations that the predominantly Arab Muslim north neglects the black and animist south and is trying to impose Arabism and Islam on it.
Some experts in Khartoum try to convince the south that many of its problems are no different than those of the north. ''The issue is that when things are bad in the north, they're even worse in the south,'' said professor Muhammad Omar Bashir of Khartoum University's Institute for African and Asian Affairs.
The peace agreement signed by representatives of the north and the south in the Ethiopian capital of Addis Ababa on Feb. 28, 1972, provided autonomy for the southern part of Sudan.
But moves, supported by President Jaafar Nimeiry, to divide the south into the three provinces that existed under British colonial rule are seen by opponents of the plan as undermining even this one achievement of the Addis Ababa agreement.
Last December, Nimeiry visited Rumbek, an educational center and former civil war hot spot in the south. He was one of a handful of top-level government officials to have visited the south in the past two years. While there, he reviewed a parade which included students from the city's renowned boarding school. Students from the school passed by the reviewing stand shouting slogans against division, their clenched fists pointing to the sky.
Mr. Numeiry closed the school indefinitely.
Well-informed souces in Khartoum said the students have since disappeared into the bush. ''They have become an embryo cell of dissidents with no difficulty in arming themselves,'' one source said.
Education problems strike a sensitive cord in the south. Southerners charge that education is used to ''Arabize'' their part of the country.
The teachers sent from the north, they say, speak only Arabic, forcing their children to abandon English - traditionally the lingua franca in southern schools.
The vice-chancellor of Juba University, a member of the Muslim Brotherhood which dominates the legislative assembly in the south, is reported to be particularly vigorous in imposing Islam on campus.
The south suffers chronic fuel shortages, constant power outages, and poor health services. Government employees complain of long delays in receiving their salaries. Politicians from the south charge that not one economic project has been launched in their region since the conclusion of the Addis Ababa agreement.
Already existing tensions within the Sudanese armed forces have been aggrevated by the growing conflict between north and south.
Units of the Anya Niya, the rebel army which fought the civil war, were absorbed into the Sudanese armed forces following the Addis Ababa agreement.
But southern units refuse to rotate to the south and recently barricaded themselves in their barracks. Southern politicians rather than Army officers were forced to negotiate an end to the crisis.
Last month 13 merchants, most of them northerners, were gunned down by a band of armed men - reported to have numbered several hundred - at the southern railway station in Ariat just north of Aweil.
The identity of the band is not known. But diplomats and government officials in Khartoum say that Anya Niya II, a group naming itself after the original rebel army, may have been involved in the killings.
The government initially blamed the attack on ''sick southern politicians,'' but later said that Libya was responsible for the slaughter.
Armed men have also harassed and robbed in recent weeks employees of Chevron Oil Company in the south. Southerners are bitterly opposed to the oil pipeline from the vicinity of the upper Nile city of Benitu, where Chevron struck oil, to Port Sudan in the northeast. They had argued in favor of an oil refinery in the south.