An official with the Defense Acquisition and Procurement Agency said the bidding process was moved forward one week amid "speculation" that opening the bidding process later in the month could result in prices beyond the country's budget for the purchase, The Korea Herald reported.
"We plan to let bidders tender offers about a week earlier," a DAPA official said.
"Our first goal is to buy 60 fighter jets within the budget. As we are scheduled to make the final selection by the end of June, we may not have enough time for negotiations if we start receiving offers from mid-June.
"In addition, an earlier schedule will quiet criticism on the most-expensive procurement deal in our history."
The new aircraft would replace the Korean air force's fleets of F-4 and F-5 combat aircraft.
Competitors for the contract are Boeing's, which is offering its F-15 Silent Eagle; Lockheed Martin's with its F-35 Joint Strike Fighter; and European conglomerate EADS, which is offering its Eurofighter Tranche 3 Typhoon.
All three competitors are dangling incentives for their selection. Boeing has promised to set up an avionics maintenance, repair and overhaul facility in the country. Boeing has reportedly said it will help the T-50 trainer built by Korea Aerospace Industries bid for a U.S. Air Force contract. And EADS/Eurofighter said that it will investment $2 billion in South Korea's plan to build its own fighter aircraft.