Punjab Gov. Salman Taseer, assassinated Tuesday, had sought changes to Pakistan's blasphemy law to make it less harsh.
His views became known more widely in November when he sought pardon for a Christian woman given the death penalty after she was accused of criticizing the Prophet Mohammed.
Saturday's attack on the Church of the Two Saints in Alexandria, Egypt, after a New Year's Day mass attended by 1,000 people, killed 21 people and wounded 79, the worst such violence since 1999.
As Copts clashed with police in violent protests, Egyptian newspapers warned that civil war could erupt unless Christians and Muslims closed ranks.
Meanwhile, attacks on the Christian minority in Iraq are on the rise after a gun battle at a church in Baghdad left nearly 100 dead in October.
P.J. Crowley, a spokesman for the U.S. State Department, told reporters during his regular briefing that Washington was troubled by the string of attacks on Christians in the Middle East.
"We are deeply concerned about what seems to be an increasing trend," he said. Crowley added that he was "very wary" to make in generalizations about violence against minority in different countries, however.
"Clearly, there are pressures on minority groups in these countries and we would hope and expect that those respective governments will fully investigate these attacks and bring those responsible to justice," he said.
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