JUBA, South Sudan (AP) — Troops from South Sudan moved into an oil-rich border town claimed by Sudan as fighting intensified between the countries over who controls the area, officials said Wednesday. A South Sudan official said the fighting is "spreading all over."

The two sides fought a civil war that lasted decades, and any increase in sporadic border clashes raises the risk of a return to all-out war.

Sudanese army spokesman Col. Sawarmy Khaled told the official Radio Omdurman that the South's army attacked the border oil town of Heglig twice in the past 24 hours. Heglig is located about 100 kilometers (60 miles) to the east of the disputed region of Abyei, whose fate was left unresolved when South Sudan split last year from Sudan.

South Sudan officials would not confirm whether their troops are in control of the oil fields.

"Fierce battles are still going on and the situation has not yet been resolved," said Khaled, promising the Sudanese people their side will be victorious.

Hostilities between Sudan and South Sudan have grown in recent months, even as the south has said it is trying to avoid a return to war. The two sides never reached a deal to share the oil resources in the region or the exact location of the border, adding to the tensions.

South Sudan's army — the SPLA — said it moved into Heglig on Tuesday after repelling an attack launched by Sudanese Armed Forces against an SPLA position near the border town of Teshwin.

SPLA spokesman Col. Philip Aguer said several Sudanese MiG-29 fighter jets bombed the area on Monday and Tuesday. Aguer said several SPLA soldiers were injured in the attack but would not say how many.

"The war is widened," said South Sudan Information Minister Barnaba Marial Benjamin. "The battle is raging. It is spreading all over."

Heglig lies along the ill-defined border between the countries and has been the focal point of nearly two weeks of clashes between the armies. The region is home to oil facilities that account for around half of Sudan's oil production, a critical source of income for the country's flagging economy.

A 2009 ruling by the Permanent Court of Arbitration in the Hague placed Heglig in South Kordofan, Sudan. But South Sudan has disputed the ruling, asserting that the region is in South Sudan's Unity State.

The Khartoum government in the north warned in a Tuesday statement that it will use "all legitimate means" to respond to the alleged aggression. Sudan also said that if South Sudan resorts to war, it would only reap "failure and destruction."

Aguer said South Sudan's forces are pushing through the area to prevent further attacks from forces there.

"Our main goal is to secure the territories of South Sudan and protect its people," said Aguer. "Sudan and its allies, militiamen that have been trained in Heglig and Karsana, have been attacking us from there for last two years."

South Sudan's move into Heglig follows separate alleged attacks in South Sudan's Unity state, near Abiemnom.

Aguer said a series of bombing attacks by Sudan on Tuesday wounded four civilians. Benjamin said the target was a "strategic bridge" linking Unity with neighboring Warrap state.

Abiemnom has not been a recent site of conflict between the two countries

The continued clashes have dimmed hopes for a resolution between the two countries on a host of issues left over from their July split, including oil-sharing, citizenship issues and the demarcation of the border.

Sudan President Omar al-Bashir was scheduled to visit South Sudan for a summit on April 3 but the talks were scrapped in the wake of the clashes at the border.

President Barack Obama earlier this month called South Sudan President Salva Kiir to ensure that South Sudan's military exercises maximum restraint and is not involved in or supporting fighting along the border.

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(Photo: REUTERS/Mohamed Nureldin Abdallah)