More shops and restaurants have been added, among other enhancements in the upgrade of the terminal, home to budget carriers AirAsia and Jetstar as well as key airlines like Qantas.

The work, which began in May 2008, will wrap up by the first quarter of next year, said Changi Airport Group (CAG) spokesman Ivan Tan.

The makeover will benefit the growing number of travelers using T1 in recent years.

In the first half of the year, T1 - the smallest of the three main terminals - handled more than 30 per cent of Changi's 22.4 million travelers.

The airport, a key hub in the region, did not provide a breakdown for the other terminals.

Before Terminal 3 opened in January 2008, Changi's traffic was more or less equally split between Terminals 1 and 2.

But with low-cost carriers growing much faster than full-service airlines, and two of Changi's three biggest budget carriers housed in T1 - Tiger Airways uses the Budget Terminal - the 30-year-old terminal has been filling up.

The trend is expected to continue in the coming months.