Rebels based in South Sudan have attacked an oil pipeline in the disputed Abyei region, Khartoum says, amid worsening relations with its neighbour.
The fire in the Diffra oil field lasted for several hours before being extinguished, an army spokesman said.
The spokesman blamed the attack on rebels from Darfur, saying they had crossed the border from South Sudan.
Both rebels and the South have reportedly denied responsibility.
The accusations comes days after Sudan ordered oil companies to block South Sudan's oil from going through its pipelines to export terminals.
The blockade, which takes effect in 60 days, was imposed after Sudan's President Omar al-Bashir accused the South of backing rebels.
South Sudan denies the charges and in turn accuses Khartoum of supporting armed groups on its territory.
Relations have been fraught since South Sudan gained independence in 2011, taking with it some 75% of the former state's oil.
However, the South is landlocked and exports its oil through pipelines which run through Sudan.
'We want oil to flow'
Army spokesman Sawarmi Khaled Saad said the Justice and Equality Movement (Jem) from Darfur carried out the explosion in Diffra, after receiving "technical support from South Sudan's army".
Jem spokesperson Jibril Ibrahim Bilal denied the charges, according to the Sudan Tribune newspaper.
South Sudan also denied having any links to the blast.
"We cannot do that at a time when we want the oil to flow," foreign affairs spokesman Mawien Makol Arik told the Reuters news agency.
South Sudan gets about 98% of its revenue from its oil exports.
The flow of oil only resumed in April after production was stopped last year in a row over how much the South should pay Sudan for the use of its pipelines.
The loss of oil revenue hit both countries very hard.
On Monday, South Sudan's Information Minister Barnaba Marial Benjamin told the BBC that Sudanese troops had moved about 10km (six miles) into its territory.
Last year, the two countries appeared to be on the brink of war after Southern forces seized the Heglig oil field near Abyei before agreeing to withdraw.