(ShareCast News) - Copper producer Kaz Minerals has reached an agreement with its principal construction contractor, Non Ferrous China, to defer payment of $300m (£198m) relating to the company's Aktogay project.Under the revised terms, the construction costs which were due to be paid in 2016 and 2017 will be settled in the first half of 2018.Kaz said there was no change to the overall amount payable to NFC or the project budget of $2.3bn.It added that Aktogay remains on track to commence production from oxide ore in 2015 and production from sulphide ore in 2017.Chief executive Oleg Novachuk said: "The deferral of $300m to 2018 provides Kaz Minerals with additional liquidity during the construction and ramp up of Bozshakol and Aktogay."This agreement also demonstrates the strength of our relationship with NFC and continues our strong track record of securing support from our partners in China for these strategically important copper projects."At 0820 GMT, Kaz shares were up 3.6% at 79.05p.