.:Middle East Online:::.

KHARTOUM - Sudanese President Omar al-Bashir is to visit South Sudan on Tuesday, official media said, as tensions mount over the disputed Abyei region.

The summit between Bashir and his southern counterpart Salva Kiir comes after the two leaders held talks in Khartoum on September 3.

Bashir "will be accompanied by a number of ministers and senior officials to discuss important issues of mutual concern," the official SUNA news agency reported Saturday.

The visit comes at Kiir's invitation, it added.

At their September summit the presidents averted a shutdown of pipelines carrying South Sudanese oil through Sudanese territory for export.

Khartoum had threatened to halt the flow over alleged southern backing of rebels on Sudanese soil.

Along with the oil deal, they pledged to implement eight other long-delayed security and economic pacts.

The neighbours fought border clashes last year which sparked fears of wider conflict but tensions appear to have generally eased since September -- except over Abyei.

The African Union had proposed that a referendum be held this month to decide whether the oil-producing territory belongs to the north or south.

After the September summit, diplomats said Kiir and Bashir seemed to have reached a deal to avoid an immediate ballot.

But UN Secretary General Ban Ki-moon warned last month that "local communities may take matters into their own hands, including by unilaterally organising a referendum," with the potential for inter-communal violence.

Abyei is home to the settled Ngok Dinka, closely connected to South Sudan, as well as the Arab Misseriya who traditionally move back and forth from Sudan grazing their cattle.

Abyei is the most sensitive unresolved issue stemming from South Sudan's separation in 2011.