KHARTOUM/JUBA, July 21 (Reuters) - South Sudan on Saturday accused Sudan of launching an aerial bombardment on its side of their disputed border, but the Sudanese army denied the charge.

The two countries came close to all-out war in April following border clashes, the worst violence since South Sudan seceded and declared its independence from Khartoum a year ago under a 2005 peace agreement that ended decades of civil war.

South Sudanese military spokesman Philip Aguer said Sudanese war planes had bombed the area of Rumaker in the Northern Bahr al Ghazal border state on Friday morning.

"Two people were slightly injured," he said. "The bombing happened at 3:25 a.m. when people were still sleeping."

Sudan's army spokesman al-Sawarmi Khalid denied that its air force had carried out any such attack.

Claims of attacks are hard to verify due to a lack of access to the remote border zone although Reuters reporters have witnessed several bombings on southern territory.

Sudanese President Omar Hassan al-Bashir met his southern counterpart Salva Kiir last week on the sidelines of a summit of the African Union, their first meeting since border fighting worsened in April.

The neighbours face the threat of sanctions from the U.N. Security Council unless they peacefully resolve border, oil and other security disputes by a deadline of Aug. 2.

The Security Council has already expressed concern over delays in the negotiating process..

The two countries accuse each other of supporting rebels on their respective territory and argue over how much landlocked South Sudan should pay to export oil through a Red Sea port in the north.

Juba shut down in January its entire oil output of 350,000 barrels per day to stop Khartoum taking some oil for what the latter calls unpaid export fees. Oil is the lifeline of both economies.

(Reporting by Ulf Laessing and Khalid Abdelaziz; Editing by Roger Atwood)