Bombs with thermitic compounds would suffice. They burn at temps over 5,000°F, and continue burning until all the explosive is oxidized. Which usually takes at least a couple days. High Explosive Incendiary (HEI) could be used, too. And, just for good measure, since these types of labs usually have an underground complex too, I would prescribe leading with some form of guided hard target penetrator, followed up by a few guided bombs after that. Completely level the structure, and burn/bury the whole thing out of existence.