The U.N. peacekeeping mission in Central African Republic is adding hundreds of troops and police before next month's elections, but their arrival is expected to be too late for Pope Francis' visit to the violent country.

A U.N. official said Tuesday the mission and the Vatican are discussing security in Central African Republic, where a recent surge in killings forced the elections to be delayed from October.

The pope is visiting three African countries from Nov. 25 to Nov. 30. Protecting him in Central African Republic is a major security challenge as violence between Christians and Muslims continues in the capital, Bangui.

The U.N. official spoke on condition of anonymity, without authorization to speak publicly.

The pope has said he wants to promote mercy in the "afflicted and tormented nation."