i2c - Using internal pull-ups for TWI on AT32UC3B?

Does anyone know if it's possible to use the built-in pull-ups for TWI on the at32uc3b chips? I've been adding external pull-ups to my TWI circuits in the past because I couldn't find any concrete info about this. But if it's possible to just use the internal pull-ups, I'd much rather do that.

Thanks!