The kidnappers of two Iraqi Roman Catholic priests backed out of a release agreement and demanded more ransom money, a Christian group has reported.

After an agreement was reportedly reached, a number of news agencies claimed that the priests were freed by the unknown group in northern Iraq that kidnapped them Saturday.

However, the kidnappers are still holding them captive and have raised the ransom amount, according to the Middle East Concern.

The abducted priests have been identified as Father Pius Affas, who is in his 60s, and Father Mazen Ishoa, who is in his 30s. Affas, a priest for over 40 years, is the rector of Mosul's Biblical Centre for lay people, among his other roles. Ishoa, on the other hand, was ordained only last month.

On Sunday, Pope Benedict XVI had personally appealed for the priests' release when the ransom was said to be $1 million, according to Reuters.

"I appeal to the kidnappers to release these two priests quickly and I underline once again that violence cannot bring relief to this tense situation," he said.

In recent months, threats, kidnappings and vandalism have increased against Iraq's Christian minorities.

The Rev. Canon Andrew White, vicar of one of the largest churches in Iraq, said 36 of his own congregants were kidnapped in July alone when he testified before the U.S. Commission on International Religious Freedom (USCIRF) on the situation in Iraq.

"The situation is more than desperate," the Baghdad church head had lamented.

Before the 2003 U.S.-lead offensive, an estimated 1.2 million Christians lived in Iraq. Now only about 600,000 remain. According to church leaders, an estimated 30 percent of the country's Christian population lives in the north, with the largest Christian communities located in Mosul, Erbil, Dohuk, and Kirkuk.

USCIRF, a bipartisan government task force responsible for monitoring religious freedom in the world, has urged the U.S. government to address the serious threats to Iraq's religious minorities and has specifically mentioned the Chaldo-Assyrian Christians as one of the communities facing intense persecution and possible "extinction" in Iraq.

Assyrian Christians draw their lineage back to Babylonian times and are one of the oldest Christian communities in the world.

Syrian Catholic Archbishop Basile Georges Casmoussa is reportedly involved in negotiations to free the two priests.