CAIRO (Reuters) - Egypt's most active militant group, Ansar Bayt al-Maqdis, denied in a Twitter message on Tuesday that it had pledged allegiance to Islamic State and it distanced itself from a statement that appeared in its name online. A statement purporting to be from Ansar appeared late on Monday on two jihadist Twitter feeds, saying the group had pledged loyalty to Abu Bakr al-Baghdadi, head of Islamic State, an al Qaeda offshoot which has seized territory in Iraq and Syria and is **w facing U.S.-led air strikes. ...