By Andrea Shalal-Esa

WASHINGTON, Nov 7 (Reuters) - If South Korea decides to order Lockheed Martin Corp F-35 fighter jets for delivery in 2017, the aircraft would come with the software needed to carry a full load of weapons, Lockheed and the Pentagon's F-35 program office said Thursday, refuting a claim made earlier this week by a Boeing consultant.

South Korea is expected to confirm in coming weeks that it needs radar-evading capabilities such as those offered by the F-35, after an acquisition task force last month rejected a bid to buy Boeing Co's F-15.

Boeing and its supporters are now pressing for a split buy of Boeing F-15s and Lockheed F-35s, arguing that South Korea would need the greater weapons-carrying capacity of the Boeing planes to counter a possible North Korean threat.

They say the F-15 is a proven aircraft that can carry more weapons at high speeds and over longer distances than the F-35, which could be critical in a war with the North.

Ron Fogleman, who served as U.S. Air Force chief of staff from 1994 to 1997 and now works as a consultant for Boeing, told reporters on Monday that delays in the development of the F-35 software meant Boeing's F-15 would be able to carry more weapons when South Korea starts to retire its current F-4 and F-5 fighters in 2016 and 2017.

But officials with Lockheed and the F-35 program office told Reuters the 3F software would be released to the F-35 fleet in the third quarter of 2017. That would allow the jet to achieve its full combat capability and carry a full load of weapons in time for the delivery schedule that South Korea is seeking, they said.

Lockheed planned an initial release of the 3F software for developmental flight testing in September 2014, said company spokesman Eric Schnaible.

South Korea has said it needs delivery of the first new fighter jets in 2017 so it can start replacing its aging current fleet of warplanes. To ensure delivery in 2017, Seoul would have to place initial orders of F-35 jets in the ninth batch of jets, which is expected to carry the 3F software.

"If (the South Koreans) decide to procure F-35s, then aircraft ordered in lot 9 or later will be configured with 3F software," said Rear Admiral Randy Mahr, deputy F-35 program manager, in a statement responding to a Reuters query.

The Pentagon hopes to award Lockheed a contract for advanced procurement of titanium and other materials for that ninth batch of jets by the end of this year.

The Pentagon's chief weapons buyer, Frank Kendall, on Thursday said the F-35 program had made sufficient progress to allow the department to budget for increased production of the new planes, but said more work was needed on software, reliability and a complex logistics system.