The leading U.S. Catholic bishop has called on President Barack Obama to protect Iraqi Christians from attacks from Islamic militants.

Al Qaeda gunmen killed 58 worshippers and wounded 75 more in an attack during worship services at the Syrian Catholic cathedral in Baghdad on October 31. In addition, Christian neighborhoods in Iraq have been blasted this week by roadside bombs and mortar shells, killing at least five people.

"Having invaded Iraq, our nation has a moral obligation not to abandon those Iraqis who cannot defend themselves," Cardinal Francis George of Chicago, the head of the U.S. Conference of Catholic Bishops, wrote in a letter to the White House.

At their meeting in Baltimore, Md., George told his fellow bishops the desperate plight of Iraqi Christians is a tragic consequence of America's 2003 invasion.

National Security Council Spokesman Mike Hammer condemned the attacks and says that the U.S. will help the Iraqi government "intensify its efforts to protect all Iraqi citizens, including vulnerable religious minorities."

Christians make up less than 3 percent of the Iraqi population.The majority of the population is Muslim.