A boy was killed and at least two people were wounded Monday when Sudanese aircraft bombed an area near a major town in South Sudan, an official and witness said, increasing the threat of a full-scale war breaking out between the two nations.

The bombing came hours after Sudanese armed forces launched an attack on Sunday more than six miles (nine kilometers) inside South Sudan's border. The attacks come just days after the south announced it was pulling its troops from a disputed border town to avoid an all-out war between the two neighbors.

Maj. Gen. Mac Paul, the Deputy Director of Military Intelligence for South Sudan, said that two MiG 29 jets belonging to Sudan dropped three bombs, two of which landed near a bridge that connects Bentiu, the capital of Unity State and Rubkona.

Mac Paul said the other bomb exploded in Rubkona market, a major population area.

"The bombing amounts to a declaration of war," Mac Paul said.

An Associated Press reporter saw the body of a boy killed in the market blast and at least two people wounded.

Sudan and South Sudan have been drawing closer to war in recent months over the sharing of oil revenues and a disputed border.

Sunday's military attack came hours after a Muslim mob burnt a Catholic church in Sudan frequented mostly by South Sudanese. The church in Khartoum's Al-Jiraif district was built on a disputed plot of land, but the Saturday night incident appeared to be part of the fallout from ongoing hostilities between Sudan and South Sudan over the oil-rich town of Heglig.

Mac Paul said late Sunday that South Sudan was building up its forces because they think Sudan is also doing the same.

The international community, led by the U.S., has called for the two countries to stop all military actions against each other and restart negotiations to solve their disputes.

President Barack Obama on Friday asked the presidents of Sudan and South Sudan to resume negotiations and said that conflict is not inevitable.

Talks between the two countries over the unresolved disputes, that were being mediated by the African Union, broke down in Ethiopia earlier this month.

The African Union on Sunday called on Sudan and South Sudan to end "senseless fighting."

South Sudan broke away from Sudan in July last year after an independence vote, the culmination of a 2005 peace treaty that ended decades of war that killed more than 2 million people. Despite the treaty, violence between the two countries has been on the rise.