He said Firefly had asked for space at KLIA2.
The turboprop operator currently operates out of Skypark Terminal in Subang after it ceased its jet operations last December as part of a wider network rationalisation by parent Malaysia Airlines (MAS).
"Presently, the 12 low-cost carriers are operating in LCCT and we expect one or two more budget airlines (Malindo and Firefly, to operate out of KLIA2), Mohd Zaifuddin said at the installation of the roof thrust of KLIAs's skybridge structure here on Friday, which symbolised the completion of the SkyBridge connection.
"All of these carriers will move to KLIA's (once it is ready) and the transfer is (to happen) overnight."
AirAsia, which will be the largest user of the new terminal, had on Oct 22, for the first time openly agreed to move to KLIA2 after years of disputes with MAHB over issues from its original site and the airline's requirements to concerns over possible hikes in airport and aeronautical charges such as office rentals, landing and parking fees.
Mohd Zaifuddin also said the service level agreement (SLA) - which will formally define the level of service the airport operator is to provide at KLIA2 - between MAHB and AirAsia as well as MAS, is being studied now and will be finalised soon.
"There are one or two issues that still need to be discussed with AirAsia, such as the check-in system, but we're in the brink of clearing that." Mohd Zaifuddin said the RM4 billion terminals is designed for a capacity of 45 million passengers per year.
"However, we expect (to handle) 20 million passengers in the first year of operations."
KLIA2 is being constructed in stages where the physical completion of the terminal is slated for end-January; while infrastructure completion is estimated by end-March.
"We're 70% complete now and on track to open to May 1.
It will be the biggest purpose-built LCCT in the world," he said, adding that it intends to capture 50% of the budget carrier market in the world.
Meanwhile, the RM150 million skybridge at KLIA2 spans 300m, with 60m of walkalators.
It will connect KLIA2's passenger terminal building to the KLIA satellite building.