LONDON (AP) — A British official heading an investigation into London's Grenfell Tower blaze that killed 71 people says she has been shocked by poor construction practices and inadequate building fire safety regulations that allow some builders to cut corners.

In an interim report, Judith Hackitt said current regulations are too confusing and accountability for compliance is poor. She said Monday: "The mindset of doing things as cheaply as possible and passing on responsibility for problems and shortcomings to others must stop."

The fire engulfed Grenfell Tower, a high-rise residential building in west London, in June. The flammable exterior cladding installed on the tower's facade has been blamed for the rapid spread of the blaze. Officials later found that hundreds more buildings could be at risk because they had similar cladding.