Force at first

Question
Ground ball to any infielder, throw to first, first baseman jumps to catch high throw, comes down on bag inadvertently as he is reaching out to tag the runner which he does but the ball comes out of his glove on contact with the runner.
Safe or out?

The force and the tag happen almost simultaneously but the force happened first.

Quote any MLB rule that applies please. (I can't find any).

I called the runner safe, got no argument but that doesn't mean much in this case. The best answer I have gotten is safe because the fielder did not maintain control of the ball. Others say, once he touched the bag the runner is out, remember, the force was not intentional. I would like to know the correct call please.

Answer
Eric,

The rule requires that the fielder maintain possession during the tag or the force play.  If I, as an umpire, judge that the fielder did not maintain possession, and that the release of the ball was not deliberate and intentional, I probably have the runner safe.  This of course is based on the fact that you said both happened simultaneously.

The reference point here is 2.00-TAG:
"A TAG is the action of a fielder in touching a base with his body while holding the ball securely and firmly in his hand or glove; or touching a runner with the ball, or with his hand or glove holding the ball, while holding the ball securely and firmly in his hand or glove. It is not a tag, however, if simultaneously or immediately following his touching a base or touching a runner, the fielder drops the ball. In establishing the validity of the tag, the fielder shall hold the ball long enough to prove that he has complete control of the ball. If the fielder has made a tag and drops the ball while in the act of making a throw following the tag, the tag shall be adjudged to have been made."

I hope this has helped.

-Martin Hoover