Al Qaeda's leader is calling on Muslims to kidnap Westerners in exchange for the release of captured terrorists.

Ayman al-Zawahri said captured Westerners could be used to negotiate for the release of imprisoned jihadists, like the blind Egyptian sheikh who plotted the 1993 bombing of the World Trade Center.

"This is the only language which they understand," said al-Zawahri, appearing in a two-hour video posted to jihadist websites. "We will keep on seizing more ... until we free our captives."

Al-Zawahri also urged jihadists to join the uprising to take over Syria, and he called for the implementation of Islamic "shariah law" in Egypt.

Al-Zawahri was born in Egypt, and got his start in radical Islam through the Egyptian Muslim Brotherhood, which is now in charge of that country.