Update at 6:25 p.m. ET: Facebook has apparently taken down the account of at least one group threatening a New Year's attack on Egyptian Christians. An Arab-language Facebook page (not linked to in the story but monitored by msnbc.com reporters) no longer loads.

Original post: The Egyptian military said Friday that it was increasing security at churches across the country before the anniversary of a deadly New Year's attack on Coptic Christians in Alexandria.

The heightened state of alert before New Year's celebrations and the Coptic Christmas season came as anonymous threats against the Copts circulated on Facebook.

 One of those on Friday threatened a suicide bombing of an unnamed church in Egypt and said that the church's name would be posted at 11:50 p.m. local time Saturday just before the attack. A spokesman for Facebook said it was aware of the threat "and is investigating it."

The Alexandria attack occurred just after midnight Jan. 1 as worshippers left a New Year's Mass. More than 20 people were killed, making it the worst violence against the Christian minority in Egypt in a decade.

The military said that it would work closely with internal security forces, revolutionary youth groups and various political forces inside Egypt to ensure the safety of Christian worshippers across the country.

In addition to New Year's Eve Masses, Egyptian Copts are preparing for the Orthodox Church's Christmas on Jan. 7. This year's Christmas celebrations and mass at the cathedral in Cairo will be attended by a senior delegation from the Muslim Brotherhood. It's the first time in nearly 30 years that the church has invited the Islamist group -- outlawed during the Mubarak regime -- to attend the Mass and celebrations.

NBC News correspondent Ayman Mohyeldin reported from Amman, Jordan. NBC's Jacob Keryakes and msnbc.com's Suzanne Choney contributed to this report.