Under pressure from four US senators, Apple has said it will start rejecting iPhone applications that tip drivers off about police checkpoints for drunken driving.

Apple updated its app developer guidelines Wednesday to exclude such apps. Yesterday, some DUI apps were still available in the App Store, but Apple usually gives developers a chance to update their apps so they can conform to the new guidelines before booting them.

The apps often combine warnings about DUI checkpoints with warnings about speed traps and red-light cameras. Users of the applications help create the warnings by registering the locations.

An Apple spokesman had no comment on the change in the guidelines, and wouldn’t say why the change was made.