Jet Airways, China Eastern Airlines, Qatar Airways and United Airlines - will move to Changi Airport's Terminal 3 on Wednesday. -- PHOTO: CAAS

They join Singapore Airlines which has been operating out of the new facility since January.

No major confusion is expected but the Civil Aviation Authority of Singapore (CAAS) will have customer service officers at Terminals 1 and 2 in case passengers and visitors end up at the wrong place.

Affected airlines say they have also informed their passengers of the move.

Mr Gerry Oh, Jet Airways' regional vice-president (South-east Asia) told The Straits Times on Tuesday: 'This is not a sudden move. We've known for the last few months we will be shifting to T3 so our travel agents and reservations people have been keeping our customers updated.'

Travellers can also refer to their tickets to find out which terminal the airline is flying out of, he said.

The Indian private carrier currently flies out of Singapore to New Delhi, Mumbai and Chennai.

To prepare for the move, the airlines have also undergone systems trials at the new terminal since February, the CAAS said in a statement on Tuesday.

Live trial flights were also conducted to test actual passenger departure and arrival processes.

The four new airlines will operate a total of 148 to and fro flights a week between Singapore and 12 cities that include Shanghai, Jakarta, Hong Kong and Tokyo.

It will bring to more than 900 the number of flights a week in and out of Terminal 3.

Among the four new kids on the block, China Eastern Airline's flight will be the first to arrive at and depart from the new terminal.

Flight MU545 from Shanghai is scheduled to land at Terminal 3 at 8.50pm on Tuesday and depart at 6am on Wednesday.