Al-Qaida's No. 2, Ayman al-Zawahiri, called for Muslim unity in a new audiotape released Tuesday by a US group that tracks extremist messages. The Washington-based SITE Institute released a transcript of the audio, which it said it had intercepted from Islamic militant Web sites where his messages are usually posted. SITE said the multimedia arm of al-Qaida, as-Sahab, claimed to have produced the 41-minute audiotape. On the tape, al-Zawahiri warned of an escalating threat from the Taliban in Afghanistan and called on all Muslims to strive for unity, "even if they are Afghans, Persians, Turks or Kurds," according to a transcript from SITE.