Gibson allegedly threatens arson in 4th audio clip

A screaming, breathless Mel Gibson allegedly demands oral sex from girlfriend Oksana Grigorieva — and then threatens to burn her house down — in the latest, expletive-filled audio clip of their fiery phone conversation released Wednesday at Radaronline. (Listen to the audio here. Warning: explicit, offensive content.)

The 54-year-old "Braveheart" actor and director reaches his boiling point in the new clip, in which he furiously complains that she had recently refused him sex by falling asleep.

When Grigorieva (mother to his 8-month-old daughter Lucia) asks for the number of his therapist, he angrily quips: "You wanted the number of my therapist? Don't you ever speak to him! Find your own goddamn therapist! Because you've got problems more than me!"

As their spat goes on and on, he adds, "You gotta push my f------ buttons. And it's not going to work with us! It's not! I can't get like this're a liar and you're dishonest and you're f----- up! So you stay the f--- away from me...I better have my daughter!"

Locked in a custody battle, the ex-lovers have both filed restraining orders against one another. Radar reports that L.A. Sheriffs are investigating Gibson for domestic violence, and he may meet with authorities next week.