Sudan is bombing oil-rich regions of South Sudan in order to scare away American and Chinese investors, South Sudanese officials have claimed, as Barack Obama expressed concern about the growing tensions between the two countries.
Barnaba Marial Benjamin, a South Sudan government spokesman, said Sudan is bombarding disputed areas in South Sudan despite a non-aggression and co-operation pact signed by both countries in African Union-led negotiations on 10 February.
"As we speak today they are continuing bombing villages," Mr Benjamin said.
Sudan described as "false and unfounded" claims by South Sudan that Khartoum was attacking southern Sudan territories. A statement issued by Sudan's delegation to the talks to resolve disputes between the two countries in Addis Ababa, Ethiopia, instead accused South Sudan of attacking a region in Sudan.
President Obama asked South Sudan's President Salva Kiir in a telephone conversation to ensure that South Sudan's military exercises maximum restraint and is not involved in fighting along the border, according to a statement from the White House.
Meanwhile, the UN Secretary General Ban Ki-moon called on the governments of Sudan and South Sudan "immediately to cease hostilities" and implement agreements already reached on security, border monitoring and the disputed border region of Abyei, the UN spokesman Martin Nesirky said.
Mr Ban called on the Sudanese President Omar al-Bashir to meet with Mr Kiir as soon as possible. A meeting scheduled between the two leaders for yesterday was cancelled by Sudan.