|Sudan's military spokesman, Al Sawarmi Khalid, responded to the claims, saying they are false [Reuters]
South Sudan's armed forces have accused Sudan of killing 17 southern civilians in airstrikes, and said it had put its troops in the disputed border region on "maximum alert".
Sudan's military spokesman denied the accusation on Thursday, saying the armed forces had not carried out any bombings in South Sudan.
South Sudan seceded in July under a 2005 peace deal that ended decades of civil war between north and south, but the two have remained at loggerheads over unresolved issues including oil, the disputed Abyei region and the location of the border.
The two sides have traded accusations of backing fighters on either side of the border. Their armed forces clashed in a rare direct confrontation in a disputed region this month.
South Sudan's military spokesman Philip Aguer said Sudanese forces continued to bomb on Thursday, in what he said
was the second day of intensified airstrikes.
"Seventeen people have been reported killed" in the Western Bahr el-Ghazal state, he said. "These were cattle herders."
"Since there are signs of ground movement by ground forces, we have alerted our forces to be on maximum alert."
Al-Sawarmi Khalid, Sudan's military spokesman, said the report had "no basis in truth."
"We have not entered or bombed any place in South Sudan and we have no targets inside South Sudan," he said.
Separately, Khartoum said on Thursday it had filed a complaint against South Sudan to the United Nations Security Council, saying some 350 rebel fighters from the western Darfur region had crossed the border into South Sudan.
"Sudan has asked the international organisation to help it apply pressure on South Sudan to prevent it from giving aid to this force, to disarm it, and deliver the ones who are wanted to justice in Sudan," El-Obeid Morawah, spokesman for Sudan's foreign ministry, said in a statement.
Some two million people have died in Sudan's civil war, waged for all but a few years between 1955 and 2005 over ideology, ethnicity, religion and oil. Under the peace deal that ended the war, the south held a referendum and voted overwhelmingly for independence.