Abstract: Locks and seals for containers, in particular those including an automatic self-checking and warning system against tampering, are provided. The lock has an infra-red (IR)-bases mechanism, with an IR emitter and an IR receiver, communicating through a waveguide such that an IR pulse emitted by the IR emitter can pass through the waveguide and be received by the IR receiver only when the lock is in the closed state. The seal has a U-shaped shackle engaged in a seal body irreversibly locking said shackle to the body. Only when the shackle is broken into two separate parts, each part can be rotated to disengage the cylindrical end so that the broken part may be pulled out of the body.