Clashes erupted between Sudan and South Sudan's armed forces on Monday, prompting Sudan's president to suspend a planned meeting to resolve the countries' bitter disputes.

South Sudan accused Sudan of sending warplanes to bomb two border areas and launching a ground attack on a third. Sudan accused the southern army of attacking the oil-producing Heglig region, parts of which are claimed by both nations.

The countries have been at loggerheads over a series of sensitive issues since South Sudan declared independence from Sudan in July, taking with it most of the country's known oil reserves. 

The neighbours have yet to agree on the position of their 1,800-km (1,120-mile) shared border or how much the landlocked south should pay to export oil - the lifeblood of both economies - through Sudan.

Sudan's President Omar Hassan Al-Bashir had been planning to fly to the southern capital Juba on April 3 to meet his southern counterpart Salva Kiir to try and resolve their disputes. But Bashir decided to suspend the trip after the Heglig attack, Sudan's state radio reported on Monday in a text message alert. It gave no further details and officials in Khartoum could not be reached for comment.

South Sudan's army, or SPLA, on Monday accused Sudan of bombing the disputed border areas of Jau and Pan Akuach and then moving ground forces against another area called Teshwin.

"After repulsing the attack, the SPLA pursued the withdrawing SAF (Sudanese Armed Forces) force and they captured two bases of SAF between Heglig and Teshwin," SPLA spokesman Philip Aguer said. "This is a self-defence measure by SPLA to defend itself against aggressors," he said.

Aguer said parts of Heglig were now under control of the southern army, a statement denied by Sudan.

Sudan's army spokesman Sawarmi Khalid Saad told state news agency Suna many SPLA soldiers had been killed in the fighting in Heglig. SPLA forces later withdrew towards the border, he added.

Saad confirmed fighting in the border area of Sudan's South Kordofan state and the southern Unity state. He denied there had been any fighting in Jau but did not name other locations or say who started the violence.

Sudan's government spokesman Abdullah Ali Masar accused South Sudan of attacking Heglig with the help of rebels from the Darfur region, Suna reported. Darfur is the scene of a separate near decade-long insurgency against the Khartoum government.

South Sudan secured its independence in a referendum promised in a 2005 peace deal that ended decades of civil war with the north. Each country has regularly accused the other of supporting rebels on either side of the border but direct confrontations are rare. - Reuters