  Cosmological constraints on moduli, whose coupling to matter is stronger than
Planck mass suppressed coupling, are derived. In particular, moduli are
considered to be produced by oscillating loops of cosmic strings and
constraints are obtained from their effects on big bang nucleosynthesis and
their contribution to diffuse gamma ray background and dark matter. Large
volume and warped Type-IIB flux compactifications are taken as examples where
strongly coupled moduli are present. Finally, the constraints on cosmic string
tension, modulus mass and modulus coupling constant are obtained and it is
shown that the constraints are relaxed significantly when the coupling constant
is large enough. In addition, the effects of thermal production of moduli are
considered and the corresponding constraints are derived.
