(a) The liability of the NOPs under the indemnities contained in clauses 20.1(a) and 20.2(a) is reduced proportionately to the extent that an act or omission of the Owner Participant, its directors, officers, employees, agents, contractors or Subcontractors (other than the NOPs and their subcontractors and agents) has contributed to the loss, damage or claim.
(b) The liability of the Owner Participant under the indemnities contained in clauses 20.1(b) and 20.2(b) is reduced proportionately to the extent that an act or omission of a NOP, its directors, officers, employees, agents, contractors or Subcontractors has contributed to the loss, damage or claim.