Section 4 of the Principal Act is amended, in subsection (1) -

(a) in paragraph (e), by the substitution of "subject of such contracts, or" for "subject of such contracts.",

(b) by the insertion of the following paragraph after paragraph (e):

"(f) are concerned with bid-rigging.",

and

(c) by the insertion of the following subsection after subsection (10):

"(11) In this section -

'bid-rigging' means the formation or continuation of an agreement or concerted practice between undertakings concerning or relating to their participation or non-participation in a relevant bidding process without informing the person requesting bids or tenders, and without prejudice to the generality of the foregoing includes the following:

(a) an agreement whereby one or more undertakings agree not to submit a bid or tender in a relevant bidding process, or agree to withdraw a bid or tender submitted as part of such a process;

(b) an agreement whereby one or more undertakings submit a bid or tender, as part of a relevant bidding process, on terms, or subject to conditions, arrived at in accordance with the agreement or concerted practice between such undertakings;