Pursue peace at all costs, a prominent Sudanese church leader said, as the heaviest attacks in a weeks-long standoff between Sudan and South Sudan threatened to flare into a full blown war.

Sudan's President's previous acceptance of South Sudan's independence and an offer to pursue peace by the South's President were signs of forgiveness for 55 years of war and both sides should pursue peace with the help of the international community, said The Most Rev. Daniel Deng Bul Yak, Archbishop fo the Episcopal Church in Sudan in a statement on Monday.

Rev. Deng has been a leader in peace process, along with other local and international groups, which led to a vote of secession for South Sudan last year. The latest clashes between north and south have come in the oil-rich disputed border region.

"The two presidents should not lose the great amount of goodwill from their people and that of the international community but should use it to build a strong bond between their people," he said.

"We should learn from 55 years of war and not return to it so hastily. The blood of those who fought for peace should not have been poured in vain," he said.

"We call on all sides to exercise restraint and pursue peace at all costs. God is on the side of those who seek peace."

He also called on the international community to follow through on last year's Comprehensive Peace Agreement that granted independence to South Sudan and provided a path to resolve border demarcation, among other issues.

"To the people of both countries: refuse to be incited to return to war by your respective leaderships," he said.

On Tuesday, South Sudan President Salva Kiir said bombing raids near the oil-producing border region are hostilities that have amounted to a declaration of war by the North, according to Reuters.

Two Sudanese aircraft bombed the settlements of Teschween, Panakuach and Roliaq, a spokesman for the South's army said in the report.

A day earlier Sudan denied bombings which killed two in a market near the town of Bentiu, capital of Unity state, according to the report.