(Adds reports of fighting in Heglig area)
By Ulf Laessing and Alexander Dziadosz
KHARTOUM, April 10 (Reuters) - South Sudan said on Tuesday that Sudan had attacked a disputed oil-producing border region with warplanes and artillery, in the latest flare-up of violence that has delayed a summit between the former civil war foes.
The South Sudanese army (SPLA) said the town of Teshwin in the border area had come under attack late on Monday. It said it repulsed the attack and pursued Sudanese troops into the disputed Heglig area nearby on Tuesday.
Sudan's armed forces confirmed clashes took place, but accused South Sudan for attacking the area in an effort to provoke further conflict, and said fighting was continuing.
South Sudan, which seceded in July, has been locked in a bitter dispute with Khartoum over oil payments and other issues, and clashes in the ill-defined border region last month raised concerns they might escalate into full-blown war.
"They launched a new attack, and occupied southern territory until the SPLA repulsed them," said Philip Aguer, a spokesman for the South's forces, the Sudan People's Liberation Army.
"We repulsed and pursued the SAF (Sudanese Armed Forces) up to Heglig," he said, referring to a disputed area where Sudan controls an oil field that accounts for roughly half of its 115,000 barrel-a-day output.
Al Jazeera television quoted a "government source" as saying South Sudan's army had taken control of the Heglig oil area, but Aguer said he could not confirm or deny the report.
"There is a difficulty of communication," Aguer said, saying more details would be provided on Wednesday. Sudan's armed forces spokesman could not be reached on his mobile phone for comment.
South Sudan's army briefly occupied a portion of the Heglig area last month before pulling out.
In a statement carried by the state-linked Sudanese Media Centre, Sudan's armed forces said on Tuesday they were battling South Sudan's "aggression ... on our southern border in the direction of Heglig".
The two countries are at odds over how much the landlocked South should pay to export its oil through Sudan.
South Sudan took three quarters of what was the united country's oilput when it seceded. It shut down production in January after Khartoum started taking some oil for what it calls unpaid transit fees.
Sudan's President Omar Hassan al-Bashir was meant to meet his counterpart Salva Kiir in Juba last week to defuse tensions, but he called off the summit due to the border violence.
Sudan's Foreign Minister Ali Ahmed Karti said on Tuesday Khartoum wanted the summit but needed more time to prepare.
"We don't want the summit to fail. If the summit fails nobody else will solve the problems," he said after meeting his Czech counterpart in Prague.
"We are committed to the summit, but let us delay till we are able to solve or at least discuss the problems in (a) way that the summit will be successful," he said.
Among other unresolved issues, the two sides need to mark their border and end accusations of supporting rebels in the other's territory. (Additional reporting by Jana Mlcochova in Prague; Editing by Alessandra Rizzo)